document_title: Murrysville, Pennsylvania

question_text: how far is murrysville pa from pittsburgh pa

root

text: Murrysville, Pennsylvania

text: Geography[edit]

text: Murrysville is located at 40°26′5″N 79°39′24″W / 40.43472°N 79.65667°W / 40.43472; -79.65667 (40.434828, -79.656724).[4] It is roughly 20 miles east of Pittsburgh on U.S. Route 22,[5] just east of the county line that separates Westmoreland and Allegheny counties. Murrysville is a control city on the sign for eastbound US 22 at the eastern end of I-376 in Monroeville.

tag: p

text: According to the United States Census Bureau, the borough had a total area of 36.9 square miles (96 km2), of which, 36.9 square miles (96 km2) of it is land and 0.03% is water.

text: Among the neighborhoods within Murrysville are Murrysville Heights, Heather Highlands, Franklin Estates, Settlers Ridge (The Ridge), Dunningtown, Newlonsburg, Ringertown, Sardis, and White Valley. Murrysville surrounds, but does not include, the Borough of Export, which is a separate municipal entity.

text: Surrounding neighborhoods[edit]

text: Murrysville has eight borders, including Upper Burrell Township to the north, Washington Township to the north and east, Salem Township to the south and southeast, Delmont to the southeast, Penn Township to the south, and the Allegheny County neighborhoods of Monroeville to the southwest and Plum to the west. The borough of Export is situated inside Murrysville in the south-southeast section.

text: Government[edit]

text: Murrysville is governed by a mayor (currently Regis J. Synan)[6] who is elected every two years and has executive/administrative powers, and a seven-member council, whose members are elected every four years and have precise legislative powers.[7]

text: In the mid-1970s, the community rapidly transitioned through three forms of government (township, borough, and home rule) and four legal name changes (Franklin Township, Franklin Borough, Murrysville Borough, and Municipality of Murrysville). Since 1976, it has operated under its Home Rule Charter as the Municipality of Murrysville.

text: Demographics[edit]

text: As of the census[8] of 2000, there were 18,872 people, 7,083 households, and 5,630 families located in the municipality. The population density was 511.0 people per square mile (197.3/km²). There were 7,396 housing units at an average density of 200.3 per square mile (77.3/km²). The racial makeup of the Municipality was 95.38% White, 0.61% African American, 0.05% Native American, 3.28% Asian, 0.01% Pacific Islander, 0.16% from other races, and 0.50% from two or more races. Hispanic or Latino of any race were 0.56% of the population.

text: There were 7,083 households out of which 34.5% had children under the age of 18 living with them, 71.8% were married couples living together, 5.5% had a female householder with no husband present, and 20.5% were non-families. 18.4% of all households were made up of individuals and 9.0% had someone living alone who was 65 years of age or older. The average household size was 2.63 and the average family size was 3.01.

text:
Historical population

Census
Pop.

%±

1880
81

—

1930
3,535

—

1940
3,797

7.4%

1950
4,937

30.0%

1960
8,517

72.5%

1970
12,244

43.8%

1980
16,036

31.0%

1990
17,240

7.5%

2000
18,872

9.5%

2010
20,079

6.4%

Est. 2016
20,042
[2]
−0.2%

source:,[9][10]

tag: table

text: In the Municipality population was spread out with 24.9% under the age of 18, 4.9% from 18 to 24, 24.3% from 25 to 44, 30.3% from 45 to 64, and 15.6% who were 65 years of age or older. The median age was 43 years. For every 100 females, there were 97.9 males. For every 100 females age 18 and over, there were 93.1 males.

text: The median income for a household in the Municipality was $64,071, and the median income for a family was $72,740. Males had a median income of $58,553 versus $32,567 for females. The per capita income for the Municipality was $32,017. About 2.2% of families and 2.8% of the population were below the poverty line, including 3.1% of those under age 18 and 3.9% of those age 65 or over.

text: Education[edit]

text: Murrysville is within the Franklin Regional School District. The district operates five schools: three elementary (Sloan, Heritage, Newlonsburg), Franklin Regional Middle School, and Franklin Regional High School, with Dr. Gennaro Piraino [11] as the district's superintendent. The district's high school boasts a graduation rate of 99.3% compared to the national average for public high schools of 82% [12] and is ranked #213 in Newsweek's 2016 "America's Top High Schools".[13] Private schools include Mother of Sorrows Catholic School.

text: Notable people[edit]

text:
Julie Benz (born 1972), actress
Jeremiah Burrell (1815–1856), Western Pennsylvania lawyer and judge
Bobby Engram (born 1973), Seattle Seahawks wide receiver; San Francisco 49ers assistant offensive coordinator
Eli Evankovich, PA House of Representatives, 54th District
Tom Flynn, defensive back for Green Bay Packers and New York Giants
Josiah Given (1828–1908) attorney, soldier and Supreme Court justice of Iowa
Ken Macha, Milwaukee Brewers manager
Robert Moose, Pittsburgh Pirates, pitcher 1967–1976
Manu Narayan (born 1973), actor
Candace Otto, Miss Pennsylvania 2003
Maddie Ziegler (born 2002), dancer and actress [14]
Mackenzie Ziegler (born 2004), dancer, singer, model and actress[14]

tag: ul

text: Local features[edit]

text: The Haymaker Gas Well in Murrysville was the nation's first commercial natural gas well. For some time, it remained the largest commercial gas well in the world.[15]

text: Since 1933, Murrysville has had a "tree sign" spelling out the word "Murrysville". The trees were landscaped to grow and form the letters by local Boy Scouts. The sign is situated on a large hill as one enters the Municipality from the Murrysville–Monroeville border, near U.S. Route 22. In 1947, the sign was featured in "Ripley's Believe It Or Not" as the world's largest arboreal sign.[16] (It is no longer the world's largest, or even the largest in the country; "Luecke", near San Antonio, Texas, is much larger.) The "Y" in the Murrysville sign points to the Haymaker Gas Well.

text: In 1977, Murrysville was designated the "Gateway to Westmoreland County" by Mayor Dollman in conjunction with the Chamber of Commerce. In 2012, community leaders upgraded sign and landscaping elaborately at the main entrance at the Allegheny / Westmoreland border featuring this designation. As is shown at the introduction of this page, the Gateway designation is featured on the official Seal of the Municipality.


document_title: St George's Chapel, Windsor Castle

question_text: when was st georges chapel at windsor castle built

text: St George's Chapel, Windsor Castle

text: History[edit]

text: In 1348, King Edward III founded two new religious colleges: St Stephen's at Westminster and St George's at Windsor. The new college at Windsor was attached to the Chapel of St Edward the Confessor which had been constructed by Henry III in the early thirteenth century. The chapel was then rededicated to the Blessed Virgin Mary, Edward the Confessor and George the Martyr. Edward III also built the Aerary Porch in 1353–54. It was used as the entrance to the new college.

text: St George's Chapel became the Mother Church of the Order of the Garter, and a special service is still held in the chapel every June and is attended by the members of the order. Their heraldic banners hang above the upper stalls of the choir where they have a seat for life.

text: The period 1475–1528 saw a radical redevelopment of St George's Chapel under the designs of King Henry VII's most prized counsellor Sir Reginald Bray (later Chancellor of the Duchy of Lancaster), set in motion by Edward IV and continued by Henry VII and Henry VIII. The thirteenth-century Chapel of Edward the Confessor was expanded into a huge new Cathedral-like chapel under the supervision of Richard Beauchamp, Bishop of Salisbury, and the direction of the master mason Henry Janyns. The Horseshoe Cloister was constructed for the new community of 45 junior members: 16 vicars, a deacon gospeller, 13 lay clerks, 2 clerks epistoler and 13 choristers. The choristers of St George's Chapel are still in existence to this day, although the total number is not fixed and is nearer to 20. The choristers are educated at St George's School, Windsor Castle. They are full boarders at the school.  In term time they attend practice in the castle every morning and sing Matins and Eucharist on Sundays and sing Evensong throughout the entire week, with the exception of Wednesdays.

text: St George's Chapel was a popular destination for pilgrims during the late medieval period. The chapel was purported to contain several important relics: the bodies of John Schorne and Henry VI and a fragment of the True Cross held in a reliquary called the Cross of Gneth. These relics all appear to have been displayed at the east end of the south choir aisle.

text: The Chapel suffered a great deal of destruction during the English Civil War. Parliamentary forces broke into and plundered the chapel and treasury on 23 October 1642. Further pillaging occurred in 1643 when the fifteenth-century chapter house was destroyed, lead was stripped off the chapel roofs, and elements of Henry VIII's unfinished funeral monument were stolen. Following his execution in 1649, Charles I was buried in a small vault in the centre of the choir at St George's Chapel which also contained the coffins of Henry VIII and Jane Seymour. A programme of repair was undertaken at St George's Chapel following the Restoration of the monarchy.

text: The reign of Queen Victoria saw further changes made to the architecture of the chapel. The east end of the choir was reworked in devotion to Prince Albert; the Lady Chapel, which had been abandoned by Henry VII, was completed; a royal mausoleum was completed underneath the Lady Chapel; and a set of steps were built at the west end of the chapel to create a ceremonial entrance to the building.  In the 21st century, St George's accommodates approximately 800 persons for services and events.[1]

text: Queen's Beasts[edit]

text: On the roof of the chapel, standing on the pinnacles, and also on pinnacles on the sides, are seventy-six heraldic statues representing the Queen's  Beasts, showing the Royal supporters of England. They represent fourteen of the heraldic animals: the lion of England, the red dragon of Wales, the panther of Jane Seymour, the falcon of York, the black bull of Clarence, the yale of Beaufort, the white lion of Mortimer, the greyhound of Richmond, the white hart of Richard II, the collared silver antelope of Bohun, the black dragon of Ulster, the white swan of Hereford, the unicorn of Edward III and the golden hind of Kent.[2]

text: The original beasts dated from the sixteenth century, but were removed in 1682 on the advice of Sir Christopher Wren. Wren had condemned the Reigate stone, the calcareous sandstone of which they were constructed. The present statues date from 1925, when the chapel was restored.[3][4]

text: Order of the Garter[edit]

text: Garter Service[edit]

text: Members of the Order of the Garter meet at Windsor Castle every June for the annual Garter Service. After lunch in the State Apartments in the Upper Ward of the Castle they process on foot, wearing their robes and insignia, down to St George's Chapel where the service is held. If any new members have been admitted to the Order they are installed at the service. After the service, the members of the order return to the Upper Ward by carriage or car.

text: The Order formerly had frequent services at the chapel, but, after becoming infrequent in the 18th century, they were discontinued in 1805. The ceremony was revived in 1948 by King George VI for the 600th anniversary of the founding of the Order, and has since become an annual event.

text: Heraldry[edit]

text: After their installation, members are each assigned a stall in the chapel choir above which his or her heraldic devices are displayed.

text: A member's sword is placed below a helm which is decorated with a mantling and topped by a crest, coronet or crown. Above this, a member's heraldic banner is flown emblazoned with his or her arms. A Garter stall plate, a small elaborately enamelled plate of brass, is affixed to the back of the stall displaying its member's name and arms with other inscriptions.

text: On a member's death, the sword, helm, mantling, crest, coronet or crown, and banner are removed. A ceremony marking the death of the late member must be held before the stall can be assigned to anyone else. This ceremony takes place in the chapel, during which the Military Knights of Windsor carry the banner of the deceased member and offer it to the Dean of Windsor, who places it on the altar.

text: The stall plates, however, are not removed; rather, they remain permanently affixed somewhere about the stall, so the stalls of the chapel are festooned with a colourful record of the members throughout history.

text: Chantries[edit]

text: St George's Windsor is among the most important and ambitious medieval chantry foundations to have survived in England. The college, itself a medieval chantry, also contains a number of independent chantries in the form of altars and small chapels dedicated to various members of the English monarchy and also to a number of prominent courtiers, deans and canons. Masses, the Office and prayers would be offered in these chantries for the good of the founder. Henry VIII had intended a chantry to be set up in the chapel, despite the fact that he instituted the religious changes which brought about the Reformation in England and the eventual suppression of chantries.

text: The much-admired iron gates in the sanctuary of the chapel as well as the locks on the doors of the chapel are the work of the medieval Cornish metalsmith John Tresilian.[5] The status of the college as a royal foundation saved it from dissolution at the Reformation. As a result, many of the smaller chantries within the chapel were preserved. These are the only remaining chantries of their kind in England which have never formally been suppressed.

text: Rutland Chantry[edit]

text: The Rutland Chantry, forming the northern transept of St George's Chapel, was founded in 1491 to honour Sir Thomas St Leger (c.1440–1483) and Anne of York, Duchess of Exeter (1439–1476)[6]; Sir Thomas was Anne's second husband. She was the eldest surviving daughter of Richard Plantagenet, 3rd Duke of York, and thus elder sister of kings Edward IV (1442–1483, reigned 1461–1483) and Richard III (1452–1485, reigned 1483–1485). A monumental brass in memory of Anne of York and Sir Thomas survives on the east wall of the Rutland Chantry, the inscription of which records that the chantry was founded "with two priests singing forevermore":

text: "Wythin thys Chappell lyethe beryed Anne Duchess of Exetur suster unto the noble kyng Edward the forte. And also the body of syr Thomas Sellynger knyght her husband which hathe funde within thys College a Chauntre with too prestys sy’gyng for ev’more. On whose soule god have mercy. The wych Anne duchess dyed in the yere of oure lorde M Thowsande CCCCl xxv"

text: The chantry received its current name in honour of the earls of Rutland, descendants of Anne and Sir Thomas; their daughter, also named Anne, married George Manners, 11th Baron de Ros and gave birth to Thomas Manners, 1st Earl of Rutland. The tomb of George and Anne Manners is a prominent feature of the chantry; their effigies are carved in English alabaster.[6]

text: Weddings[edit]

text: The chapel has been the site of many royal weddings, particularly of the children of Queen Victoria. These weddings include:

text:
Albert Edward, Prince of Wales, and Princess Alexandra of Denmark in 1863 (later King Edward VII and Queen Alexandra respectively)
Princess Helena and Prince Christian of Schleswig-Holstein-Sonderburg-Augustenburg in 1866
Princess Louise and the Marquess of Lorne (later Duke of Argyll) in 1871
Prince Arthur, Duke of Connaught and Strathearn and Princess Louise Margaret of Prussia in 1879
Princess Frederica of Hanover and Baron Alphons von Pawel-Rammingen in 1880
Prince Leopold, Duke of Albany and Princess Helena of Waldeck and Pyrmont in 1882
Princess Marie Louise of Schleswig-Holstein and Prince Aribert of Anhalt in 1891
Princess Alice of Albany and Prince Alexander of Teck (later Earl of Athlone) in 1904
Princess Margaret of Connaught and Prince Gustaf Adolf of Sweden (later King of Sweden) in 1905
Lady Helena Cambridge and Major John Gibbs, Coldstream Guards in 1919
Anne Abel Smith and David Liddell-Grainger in 1957
Lady Helen Windsor and Timothy Taylor in 1992
Prince Edward, Earl of Wessex, and Sophie Rhys-Jones in 1999
The union of Charles, Prince of Wales, and Camilla Parker Bowles in 2005 received a blessing from the Archbishop of Canterbury
Peter Phillips and Autumn Kelly in 2008
Prince Harry, Duke of Sussex, and Meghan Markle in 2018[7]
The forthcoming wedding of Princess Eugenie of York and Jack Brooksbank on 12 October 2018

text: Burials[edit]

text: The chapel has been the site of many royal funerals and interments. Persons interred here include:

text: Altar[edit]

text:
George Plantagenet, 1st Duke of Bedford, on 22 March 1479
Mary of York, in 1482
Edward IV, King of England (1461–1470; 1471–1483), in 1483
Henry VI, King of England (1422–1461; 1470–1471), reburied from Chertsey Abbey in 1484
the coffins of two unidentified children suggested to be the Princes in the Tower
Elizabeth Woodville, wife of Edward IV (1464–1483), on 12 June 1492
Edward VII, King of the United Kingdom (1901–1910), on 20 May 1910
Alexandra of Denmark, wife of Edward VII (1863–1910), on 28 November 1925

text: Quire[edit]

text:
Jane Seymour, Queen of England, in 1537
Henry VIII, King of England and Ireland, in 1547
Charles I, King of England, Scotland and Ireland, in 1649
Stillborn son of Queen Anne (last monarch of the House of Stuart), in 1698.

text: Royal Vault[edit]

text:
Princess Amelia of the United Kingdom in 1810
Princess Augusta, Duchess of Brunswick-Wolfenbüttel in 1813
Princess Charlotte of Wales in 1817
Charlotte of Mecklenburg-Strelitz, Queen of the United Kingdom, in 1818
George III, King of the United Kingdom, in 1820
Prince Edward, Duke of Kent and Strathearn in 1820
Princess Elizabeth of Clarence in 1821
Prince Frederick, Duke of York and Albany in 1827
George IV, King of the United Kingdom, in 1830
William IV, King of the United Kingdom, in 1837
Princess Augusta Sophia of the United Kingdom in 1840
Adelaide of Saxe-Meiningen, Queen of the United Kingdom, in 1849
Prince Adolphus, Duke of Cambridge (1774–1850) (reburial) in 1930
George V, King of Hanover, in 1878
Princess Augusta of Hesse-Kassel (1797–1889) (reburial) in 1930
Princess Mary Adelaide of Cambridge in 1897
Francis, Duke of Teck in 1900

text: Near West Door[edit]

text:
George V, King of the United Kingdom, in 1936
Mary of Teck, Queen of the United Kingdom, in 1953

text: King George VI Memorial Chapel[edit]

text: George VI, King of the United Kingdom, died 1952. Interred 26 March 1969 following its construction.[8]

text:
Princess Margaret, Countess of Snowdon (ashes), in 2002
Elizabeth Bowes-Lyon, Queen of the United Kingdom, in 2002

text: Albert Memorial Chapel[edit]

text:
Prince Leopold, Duke of Albany, in 1884
Prince Albert Victor, Duke of Clarence, in 1892

text: Gloucester Vault[edit]

text:
Prince William Henry, Duke of Gloucester and Edinburgh, in 1805
Maria, Duchess of Gloucester and Edinburgh, in 1807
Prince William Frederick, Duke of Gloucester and Edinburgh, in 1834
Princess Sophia of Gloucester, in 1844
Princess Mary, Duchess of Gloucester and Edinburgh, in 1857[9]

text: Other[edit]

text:
William, 1st Baron Hastings (1431–1483), a nobleman and close friend of King Edward IV; in the north aisle of St George's Chapel, next to Edward IV.
Anne St. Leger, Duchess of Exeter (1476 – 21 May 1526) and her husband George Manners, 11th Baron de Ros (22 August 1465 – 23 October 1513) in the private Rutland Chapel[10]
Charles Brandon, 1st Duke of Suffolk, in 1545
Christopher Villiers, 1st Earl of Anglesey, in 1631
Henry Somerset, 1st Duke of Beaufort (1629–1700) and his ancestors in the private Beaufort Chapel; the original monument by Grinling Gibbons was moved to St Michael and All Angels Church, Badminton, in 1878.
Very Revd Dr Penyston Booth (1681–1765), Dean of Windsor
Dejazmatch Alemayehu Tewodros, son of Emperor Tewodros II of Ethiopia, on 21 November 1879

text: In media[edit]

text:
Wenceslaus Hollar. View and Ground Plan of St. George's Chapel, Windsor ca. 1671.[11][12][13]
John Henry Le Keux. St.Georges Chapel, Windsor. Ground Plan 1810. Engraved after a plan by F.Mackenzie, published in Britton's Architectural antiquities of Great Britain, 1807. Copper engraved antique plan.[14][15]


document_title: Steve Urkel

question_text: when does steve urkel appear on family matters

text: Steve Urkel

text: Character development[edit]

text: In syndication, Steve Urkel first appeared on the 4th episode of the first season, "Rachel's First Date" (as the show staff wanted to more naturally introduce him to audiences upon repeated viewings). On the 12th episode of the first season, "Laura's First Date", he reappears as a nerdy young boy who takes Laura Winslow out on a date. While he is madly in love with her, Laura finds Steve grating and doesn't return his affection. While intended as a minor character, Urkel became very popular for his oddball antics. He soon became a recurring character, and joined the main cast beginning with the season two premiere "Rachel's Place".[8]

text: Family Matters co-creator Michael Warren named the character after his friend, writer and director Steve Erkel. Due to the show and the character's tremendous popularity during the early 1990s, Erkel encountered difficulties using his own name; he received many prank phone calls from "Laura" asking for "Steve", and businesses found his name to be suspicious. Warren stated that had he known that the character would reappear for years he would not have named him after his friend.[8]

text: Portrayal[edit]

text: An archetypal nerd, Steve Urkel is characterized as kind and well-meaning, but bungling and a meddler. He is fiercely protective of and obsessed with his unrequited love Laura Winslow, and this admiration extends to the rest of the Winslow family. However, Steve is comically clumsy and inept and his attempts to help the Winslows usually go awry. This puts him at odds with the family patriarch Carl, who routinely throws Urkel out of his house.

text: Later episodes suggest that Steve's attachment to the Winslows stems from his bad relationship with his own family. Urkel often hints that most of his relatives, including his (unseen) parents, despise him and refuse to associate with him. This culminates in the two moving to Russia without him, whereupon he moves in with the Winslows.

text: Urkel dresses unfashionably for someone his age (he is most commonly seen wearing suspenders, brightly colored shirts, and high water pants) and has a number of eccentric hobbies and interests, including Polka dancing and accordion playing. Unlike his friends, he has little interest in popular culture and athletic endeavors.

text: While he is unpopular with his schoolmates, Urkel is a brilliant student and is on a first-name basis with his teachers. He is a genius inventor as well, and his fantastical but unreliable gadgets (including a transformation device and a time machine) are central to many Family Matters plots and gags.

text: Stefan Urquelle[edit]

text: During the season five episode "Dr. Urkel and Mr. Cool," in a takeoff on The Nutty Professor films, Urkel devises a plan to win Laura's heart: transforming his DNA using a serum, which suppresses his "nerd genes" and brings out his "cool" genes. This results in the alter ego known as Stefan Urquelle, played by Jaleel White in more casual attire. Initially, Laura is enamored with the smoother Stefan, but asks that he turn back into Steve when Stefan's self-centeredness makes itself apparent.

text: Steve improves the formula in the season five episode "Stefan Returns" to reduce its negative effects on his personality, and invents a "transformation chamber" allowing him to become Stefan at will. He would change into Stefan several times – even while dating Myra – but some circumstance would force Steve to turn into his normal self again. With his narcissistic tendencies toned down, Laura falls deeply in love with Steve's alter-ego.

text: In the seventh-season finale "Send in the Clones," Steve creates a cloning machine and winds up creating a perfect duplicate of himself. Myra is initially excited, but eventually realizes that two Steves are just too much. To clear up the situation, Laura proposes that one of the Steves be permanently turned into Stefan, so that she and Myra can both be with the one they love. This Stefan becomes a recurring character and eventually proposes to Laura in the ninth season. After weighing her choices in the flashback episode "Pop Goes the Question," Laura chooses Steve over Stefan. Stefan departs and is not seen again.

text: Relationships[edit]

text: Steve had been in love with Laura since they were in kindergarten. However, she did not always reciprocate the feelings that he had for her and would date other guys more to her taste. Unlike Greta's successful warding off of Myrtle, Laura's would-be boyfriends would often bully Steve, but it always ends with him warding them off, especially when he knows most of them would end up hurting her in the end and refused to allow them to take advantage of her. Steve has shown that, unlike Myrtle, he does respect Laura's personal space. However, she has shown appreciation for Steve when he selflessly risked himself to not only protect her, but also has saved her father's life. In the ninth-season episode "Out With the Old," he finally gets himself a makeover in time for Laura's charity bachelor auction, and, though it was not a success, her feelings for him finally changed, and they eventually become engaged to be married by "Pop Goes the Question" later that season.

text: Steve had a short and brief relationship with Susie in season two, but their relationship ended when he introduced her to the president of the chess club. In the season three episode "The Love God," Vonda Mahoney also became interested in him after he tutored her for a class. Fearing that she wants to make herself "easy" for Eddie to date, Steve teaches her the dangers of it and helps her have love and self-respect for herself. Although Vonda felt better about herself, this did not sit well with Eddie, who wanted to pound Steve for it.

text: In season four's "A Thought In The Dark", Steve was set up with Ted's cousin, Myra Monkhouse (played by Michelle Thomas) so Laura could have some space from his infatuation. Although he was initially attracted to Myra because of her intelligence and sweet personality, he was soon disgusted by her jealous and possessive nature by the end of "Buds 'N Buns". This was explored in both seasons five and nine, when Steve finally saw what life was like in not only Laura's shoes, but in sense the Winslows as well. Though in love with him, Myra was also frustrated with Steve and asked him why he even loves Laura. When he agrees to go steady with her in season six's "Paradise Bluff", she did somewhat revert to the sweet, intelligent girl he was originally attracted to. By season nine, he grows apart from her as he matures and Laura started to return the feelings he had for her. In "Breaking Up Is Hard To Do," during their date at the restaurant Amour, it became clear to Steve that Myra hated his makeover and demanded that he return to the sexy nerd she loved so much. When he refused, she broke up with him first, although it later turned out to be a ploy so she could get him to renounce his love for Laura and stay with her. When that failed, Myra resorted to stalking and spying on him with illegal surveillance gear in her room with a spy cam attached to his glasses. In "Crazy For You," she teamed up with Stefan to stop Steve and Laura's date. Although initially successful, Laura still wanted to date him and Myra vowed never to stop stalking him until he took her back. In the following episode "Crazier For You," Steve has learned that Myra was spying on him and confronted her about it. He orders her to stop stalking him and renounce her love for him because he will never take her back and reaffirms his love for Laura. She refused and got Laura falsely arrested for stealing her watch. However, Steve was able to drop the charges when he exposed Myra for stalking him with illegal spy gear and the police pursued criminal charges against her. When she learned of his engagement to Laura, she continued to carry the torch even when he went into space. However, when she tried to pretend to be Urkel's fiancée, she is caught by an unseen Stefan.

text: Cultural impact[edit]

text: In 2010, Westside Middle School in Memphis, Tennessee outlined its dress code policy on sagging pants, asking students to pull them up or get "Urkeled", a reference to the character. In this practice, teachers would forcibly pull students' pants up and attach them to their waist using zip ties. Students would also have their photo taken and posted on a board in the hallway, for all of their classmates to view. In an interview with NBC affiliate WMC-TV, Principal Bobby White stated that the general idea is to fight pop culture with pop culture.[9] One teacher at the school claimed to have "Urkeled" up to 80 students per week, although after five weeks the number dropped to 18.[10]

text: Ratings effect[edit]

text: In syndication, Steve is incorporated into the teaser scene of "Rachel's First Date"; his first appearance in the original broadcasts is in the 1989 episode "Laura's First Date", in which Carl and Eddie separately set up dates for Laura for a dance or party (both terms are used in the episode), and the first thing known about him is that he allegedly ate a mouse, and he later makes reference to a mouse when speaking to Carl, implying that it might be true. Prior to Steve Urkel's introduction, the show was on the brink of cancellation due to mediocre ratings. After Urkel was introduced, several scripts had to be hastily rewritten to accommodate the character, while several first-season episodes that had been completed had new opening gag sequences filmed featuring Steve trying to push open the Winslows' front door while the family holds it shut. The addition of Steve immediately helped the show boost its modest ratings. White was credited as a guest star in the first season and became a regular member of the cast in season two.

text: The Urkel Dance[edit]

text: The Urkel Dance was a novelty dance that originated in the season two episode "Life of the Party". It was based around the character of Steve Urkel and essentially incorporated movements which made the dancer's posture more like his. The lyrics instructed the dancer how to pose:

text:
"If you want to do the Steve Urkel dance,
All you have to do is hitch up your pants,
Bend your knees, and stick out your pelvis;
(I'm telling you, baby, it's better than Elvis!)".

text: The dance was popular enough to appear on another show, Step by Step, when the Steve Urkel character appeared in a crossover in the season one episode "The Dance".

text: Jaleel White also performed the song, in character as Steve Urkel, on the 5th Annual American Comedy Awards. Bea Arthur (from Maude & The Golden Girls) joined him on stage to "Do The Urkel,[11]" after which she said, "Hey MC Hammer, try and touch that!"[12]

text: A promotional cassette single of the song that accompanies the dance was pressed and distributed in limited numbers. A T-shirt was also produced featuring lyrics and Urkel's likeness.

text: Rick Sanchez pays some form of homage to The Urkel Dance with "The Rick Dance" in the Rick and Morty episode Ricksy Business.

text: Appearances on other shows[edit]

text:
Full House – In the 1991 episode, "Stephanie Gets Framed", Steve is called in to help Stephanie Tanner (Jodie Sweetin) deal with her anxieties after she has to get glasses. He was cousin to a friend of D. J.. Incidentally, Family Matters did not air on the night of the episode's original airdate (January 25, 1991). It is implied that he found himself in San Francisco in the Full House universe before paying a visit to the Lambert household from Step by Step.
Step by Step – In the series' second episode, "The Dance", Steve lands in the Lambert-Foster family's backyard after launching himself with a rocket pack from the living room of the Winslows' house in the Family Matters episode "Brain Over Brawn" (the two scenes being shown in uninterrupted sequence, as Family Matters and Step by Step aired back to back on ABC's TGIF lineup at the time). He then helps his science-fair pen pal, Mark Foster (Christopher Castile), and lifts Alicia "Al" Lambert (Christine Lakin)'s spirits after her potential date dumps her just before a school dance. White reprises his "Do the Urkel" dance in the scene where Al gives the boy that dumped her his comeuppance. White also makes a brief two-second cameo as Steve in the 1997 episode "A Star Is Born", snapping a clapperboard on the set of the movie that Al was cast in over her two sisters.
Meego – In this short-lived series, Steve makes a non-speaking cameo appearance in the second episode "Love and Money," where he angrily retrieves a television set stolen by Meego. He then appears in the third episode "The Truth About Cats and Dogs" helping out at a model car derby competition.
Additionally, in the Family Matters episode "Beauty and the Beast," Steve sends a chain letter to his friend Cory Matthews, who lived in Philadelphia. The reference is to Ben Savage's character from Boy Meets World, but there were no on-screen crossovers. In an episode of Boy Meets World, Cory says he receives a chain letter from his friend Steve.
Fuller House - In the Season 3 finale, Urkel was mentioned by D.J.. In an interview with TVLine’s Andy Swift, series creator Jeff Franklin mentioned he is friends with White and they have talked about White reprising the role and that they had some ideas for the character if White decides to reprise the role.[13]

text: Merchandise[edit]

text: At the height of his popularity, Urkel's name was branded to several products including a short-lived fruit flavored cereal known as Urkel-Os and a Steve Urkel pullstring doll. There was also a T-shirt line that was created in 2002, but was discontinued shortly after its inception.[14]

text: Reception[edit]

text: In 1999, TV Guide ranked Urkel #27 on its list of the "50 Greatest TV Characters of All Time".[15] In 2004, he was listed at #98 in Bravo's 100 Greatest TV Characters.[16]

text: Notes[edit]

text:
Jump up ^ Carter, Bill (1997-02-05). "Steve Urkel Is a Hit Notes - Did He Do That? - Review". The New York Times. Retrieved 2009-01-23.
Jump up ^ Horowitz, Joy (1991-04-17). "Snookums! Steve Urkel Is a Hit". The New York Times. Retrieved 2010-08-20.
Jump up ^ Zoglin, Richard (1998-05-18). "Television: Another Teary Farewell". Time. Retrieved 2010-08-21.
Jump up ^ "Is Uncool Urkel the '90s Answer to the Fonz?". Los Angeles Times. 1991-01-04. Retrieved 2010-08-22.
Jump up ^ "Will the Real Steve Please Stand Up?". Los Angeles Times. 1992-02-04. Retrieved 2010-08-22.
Jump up ^ Bellafante, Ginia (1996-12-09). "Revenge of The Nerd". Time. Retrieved 2010-08-21.
Jump up ^ "Television: Yes, Urkel Still Lives". Time. 1991-04-01. Retrieved 2010-08-21.
^ Jump up to: a b Pool, Bob (1992-02-04). "Will the Real Steve Please Stand Up?". Los Angeles Times. Retrieved May 26, 2012.
Jump up ^ Bruce, Becky (December 7, 2010). "Threat of 'Urkel' solves sagging pants problem". KSL.com. Retrieved December 8, 2010.
Jump up ^ "Students get 'Urkeled' for baggy pants". ABC2. December 7, 2010. Archived from the original on December 10, 2010. Retrieved July 20, 2014.  External link in |publisher= (help)CS1 maint: Unfit url (link)
Jump up ^ Do The Urkel(.com) Archived 2010-10-15 at the Wayback Machine. - The Website
Jump up ^ The House of Diabolique vs. Bea Arthur & Urkel
Jump up ^ Swift, Andy. "Fuller House Boss Explains Steve Urkel Shout-Out: 'We Have Some Fun Ideas'". TVLine. Retrieved 1 January 2018.
Jump up ^ "Family Matters: 1989-1998". People. 2000-06-26. Retrieved 2011-08-15.
Jump up ^ TV Guide Guide to TV. Barnes and noble. 2004. p. 651. ISBN 0-7607-5634-1.
Jump up ^ "Bravo > 100 Greatest TV Characters". Bravo. Archived from the original on July 17, 2007. Retrieved November 11, 2006.

tag: ol

text: Fictional American people of Kenyan descentFictional astronautsFictional characters from ChicagoFictional musiciansFictional characters introduced in 1989Fictional characters with multiple personalitiesFictional geneticistsFictional inventorsFictional modelsComedy charactersComedy television charactersChild characters in televisionFamily Matters

text: CS1 errors: external linksCS1 maint: Unfit urlWebarchive template wayback linksArticles that need to differentiate between fact and fiction from October 2013All articles that need to differentiate between fact and fictionWikipedia articles needing style editing from March 2017All articles needing style editingArticles with multiple maintenance issues


document_title: Umbra, penumbra and antumbra

question_text: the dark part of a shadow where light from a source is completely blocked is called the

text: Umbra, penumbra and antumbra

text: Umbra[edit]

text: The umbra (Latin for "shadow") is the innermost and darkest part of a shadow, where the light source is completely blocked by the occluding body. An observer in the umbra experiences a total eclipse. The umbra of a round body occluding a round light source forms a right circular cone; to a viewer at the cone's apex, the two bodies are equal in apparent size. The distance from the Moon to the apex of its umbra is roughly equal to that between the Moon and Earth (384,402 km (238,856 mi)). Since Earth's diameter is 3.70 times the Moon's, its umbra extends correspondingly farther: roughly 1,400,000 km (870,000 mi).[1]

text: Penumbra[edit]

text:
The penumbra (from the Latin paene "almost, nearly") is the region in which only a portion of the light source is obscured by the occluding body. An observer in the penumbra experiences a partial eclipse.
An alternative definition is that the penumbra is the region where some or all of the light source is obscured (i.e., the umbra is a subset of the penumbra).  For example, NASA's Navigation and Ancillary Information Facility defines that a body in the umbra is also within the penumbra.[2]

text: Antumbra[edit]

text: The antumbra (from Latin ante, "before") is the region from which the occluding body appears entirely  within the disc of the light source. An observer in this region experiences an annular eclipse, in which a bright ring is visible around the eclipsing body. If the observer moves closer to the light source, the apparent size of the occluding body increases until it causes a full umbra.


document_title: Kaboom (Parks and Recreation)

question_text: who played the lawyer in parks and recreation

text: Kaboom (Parks and Recreation)

text: Plot[edit]

text: The episode opens with Leslie (Amy Poehler) receiving a speakerphone call about abnormal transactions on her credit card. The purchases turn out to all be legitimate, but Leslie cancels the card anyway out of embarrassment when Tom (Aziz Ansari) hears about her unusual purchases, including a "bucket of cake", a man pillow in the shape of Daniel Craig, and tuition to Hogwarts School of Witchcraft and Wizardry. Later, the parks department and Ann (Rashida Jones) visit neighboring Indiana town Eagleton to help build a playground in a single day, as part of an event by the charity KaBOOM! There, Leslie and Ann find Ann's ex-boyfriend Andy (Chris Pratt), who claims to be volunteering, but in reality, is coming for the free food. He tells Leslie and Ann that he now has a home with the drummer of his band. Leslie is inspired by the energy of the group and its leader Keef (Paul Scheer), which prompts her to take proactive measures in filling in the pit in Pawnee and turning it into a park. While discussing the matter with her parks department, Mark (Paul Schneider) takes her aside and suggests she simply fill it in without permission. Leslie decides to take his advice and rents an excavator to fill in the pit.

text: Leslie meets Ann at the pit with the rented excavator, which starts filling it in with dirt. However, they failed to realize Andy was under some tarps in the pit, and he is injured when mounds of dirt fall on him. He is taken to the hospital, where Ann is assigned as his nurse. An angry Ron (Nick Offerman) tells Leslie the town is now open to a large potential lawsuit from Andy, and he sends her to visit him along with their city attorney Scott (H. Jon Benjamin). Meanwhile, Andy is excited to be near Ann and insists it will lead to them getting back together, but Ann tells him she is very happy dating Mark, who unlike Andy has a job, apartment and future. A disheartened Andy decides he has to get money to impress Ann. When Leslie visits, he regretfully tells her he and his attorney Wendell Adams (Chris Tallman) are going to sue Pawnee.

text: Leslie is convinced she can reason with Andy if they can talk without their lawyers, but Andy will not return her calls. Finally, Ann calls Andy and asks him to come to her house. Later that day, he arrives completely naked, having assumed Ann wanted to take him back. A disgusted Ann leaves the house, leaving Leslie and Andy to talk. Andy admits he is suing the town in an attempt to win Ann back, and she thinks of a different way he can impress her. The next day at city hall, Andy tells Leslie and Scott he will drop the lawsuit if they agree to fill in the pit right away. Scott agrees, unaware it was a trick between Andy and Leslie. The next day the pit is filled in and turned into a lot, and an impressed Ann waves at Andy while the construction work is going on. The episode ends with Keef riding a motorboat, revealing his role in KaBOOM! was an elaborate prank to get the playground built, and announcing he is going to build a hospital in a poor part of China.

text: Production[edit]

text: "Kaboom" was written by Aisha Muharrar and directed by Charles McDougall. The Pawnee pit, which has been a focal plot device in Parks and Recreation since the first episode, is filled in during this episode.[1] "Kaboom" features actor and comedian Paul Scheer in a guest appearance as the KaBOOM! organizer. Scheer has previously worked with Aziz Ansari on the MTV sketch comedy show, Human Giant.[2] "Kaboom" also featured H. Jon Benjamin, a voice actor from Archer, Dr. Katz, and Home Movies, as Pawnee's lawyer.[2] Chris Pratt actually appeared naked during filming of a scene in which he arrived at Ann's house without clothes on. Michael Schur, co-creator of Parks and Recreation, said the scene was written because Pratt "loves taking his clothes off".[3]

text: The script prominently features KaBOOM!, a real-life charitable organization that builds playgrounds in locations all over the United States. Parks and Recreation included the charity in the episode as part of a charity campaign called "I Participate", sponsored by the Entertainment Industry Foundation. The campaign involves more than 60 shows on NBC ABC, CBS, Fox and several other networks, all of which spotlighted real-life charities in an effort to encourage volunteerism.[4] Greg Daniels, the series executive producer and co-creator, was responsible for choosing the KaBOOM! charity.[5] In an editorial featured on The Huffington Post after the "Kaboom" aired, KaBOOM! chief executive officer Darell Hammond called the episode "Ka-PERFECT!" and said, "The writers certainly captured the spirit that fuels each of our (playground) builds – something that inspires volunteers to continue their great work and strive even harder to give back to their communities."[6]

text: Within a week of the episode's original broadcast, two deleted scenes from "Kaboom" were made available on the official Parks and Recreation website. The first two-minute clip included extended scenes of the KABOOM! park construction, including Tom text messaging instead of working, Leslie and Ann competing with children, and Paul Scheer doing the Worm dance move. Leslie also seeks advice from her mother (played by Pamela Reed) after putting Pawnee in danger of a lawsuit. In the second, 15-second clip, Ann complains to Mark about Andy appearing naked at her apartment, which Mark only finds amusing.[7]

text: Cultural references[edit]

text: Andy says he volunteers at several organizations in order to get their free food at their events. He specifically identifies the Red Cross, which he says has "amazing cookies", and Meals on Wheels, which he described as a "bonanza".[1]

text: Reception[edit]

text: In its original American broadcast on October 22, 2009, "Kaboom" was seen by 4.98 million household viewers, according to Nielsen Media Research. It was a slight increase from the previous week's episode, "Sister City". "Kaboom" received a 2.1 rating/6 share among viewers aged between 18 and 49.[8] The episode received generally positive reviews. Steve Heisler of The A.V. Club said "Kaboom" was the best episode of the second season, and called Parks and Recreation "one of the funniest shows on TV right now".[9] Heisler praised the show for not shying away from outrageousness, and called Andy's naked entrance "by far the highlight of the series". Entertainment Weekly writer Henning Fog said "Kaboom" continued a trend of superior Parks episodes in season two, and praised the episode for filling in the pit, claiming it "both tied up a plot thread that had overstayed its welcome and put to rest any lingering ghosts from the first six episodes".[1] Matt Fowler of IGN said the episode was funny and served as good character development for Leslie and Andy. But Fowler also said "some scenes fell flat", and questioned why Ann would continue to harbor feelings for the immature Andy.[2]


document_title: Eye for an Eye (1996 film)

question_text: who plays megan in eye for an eye

question_tokens: who plays megan in eye for an eye

text: Eye for an Eye (1996 film)

text: Plot[edit]

text: Karen McCann is happily married to Mack and has two daughters, 17-year-old Julie (from Karen's previous marriage) and six-year-old Megan. She lives in a nice house in Pacific Palisades, California and has a good job in a museum.

text: Karen's world is shattered when Julie is violently raped and murdered while Karen listens helplessly on the phone from her car. Detective Sergeant Joe Denillo assures Karen there is enough DNA evidence to find and convict the killer. He encourages the McCanns to seek counseling.

text: At a support group, they meet people in similar circumstances, including Albert and Regina Gratz, and Sidney Hughes. During the meeting, Karen overhears Albert talking to Sidney about something which alarms Regina.

text: The DNA tests reveal the killer, Robert Doob, a delivery man with a criminal record. At the trial it is clear Doob is guilty, but because the defense did not receive a sample of the DNA evidence, the judge dismisses the case. Karen and Mack are dumbstruck as Doob walks free. Mack snaps and furiously attacks Doob, but is overpowered by guards and Doob walks out unharmed.

text: Mack is desperate to return to a normal life, but Karen cannot stop thinking of Doob. She finds the apartment where he lives, then keeps detailed records of his movements, stalking him. After observing Doob urinate on a customer's lawn after a delivery she goes to Denillo — but he tells her there's no evidence of intent. Karen attempts to warn the delivery customer, but the woman only speaks Spanish and does not understand her.

text: Karen later learns that the murderer of the son of a member of her support group has been killed in a drive-by shooting, just days after being released from prison. Angel, also in the self-help group, tells Karen the best way to get over her grief is to focus on the good times with her living daughter — and Karen realizes she has been so fixated on Doob that Megan has been deprived of her attention. Meanwhile, Doob has gone to Megan's school and struck up a conversation with the girl during recess. When Karen comes to pick up Megan, Doob deliberately intimidates her.

text: Worried for Megan’s safety, Karen's sanity is on the rocks and remembers what happened to the killer of her friend's son and approaches Sidney, who admits the drive-by shooting was set up by him and Martin. Karen demands their help and they agree to find a weapon, train her, and plan the murder, but tell her she has to carry it out. Karen agrees and they begin plotting. She also joins a self-defense class which helps her gain more confidence, helps rekindle her sex life with Mack, and improves her relationship with Megan. Karen feels encouraged. Although Martin doubts Karen is capable of murder, Sidney gives her a gun.

text: The next day, Angel reveals that she is really an undercover FBI Agent investigating vigilante activity. Angel warns Karen not to kill Doob. Karen calls Sidney to tell him she cannot go through with it. However, she soon changes her mind when she learns that the Hispanic customer she tried to warn about Doob has been raped and murdered, in the same way Julie had been. Karen is so furious she accuses Denillo of not finding enough evidence, letting Doob go free. Hearing Doob has again gotten off on a technicality bolsters her resolve. Karen decides that the only way to avenge her daughter's murder and save her family from Doob is to kill him.

text: She sets a trap to lure Doob into her home, so that she can say killing him was self-defense. It works. She shoots Doob dead and calls the police. Denillo arrives and tells Karen that he knows the truth and that she hasn't fooled him, to which she replies, "Prove it." He decides to tell his colleague that it was a "clear case of self-defense". When her husband arrives, he sits beside her, holding her hand, knowing what she has done.

text: Cast[edit]

text:
Sally Field as Karen McCann
Kiefer Sutherland as Robert Doob
Ed Harris as Mack McCann
Joe Mantegna as Det. Joe Denillo
Paul McCrane as Officer Neil Cole
Beverly D'Angelo as Dolly Green
Olivia Burnette as Julie McCann
Alexandra Kyle as Megan McCann
Darrell Larson as Peter Green
Charlayne Woodard as Angel Kosinsky
Philip Baker Hall as Sidney Hughes
William Mesnik as Albert Gratz
Rondi Reed as Regina Gratz
Keith David as Martin
Donal Logue as Tony
Grand L. Bush as Tyrone
Armin Shimerman as Judge Arthur Younger
Nicholas Cascone as District Attorney Howard Bolinger
Ross Bagley as Sean Kosinsky
Cynthia Rothrock as Tina
Stella Garcia as Maria

text: Critical reception[edit]

text: Eye for an Eye received negative reviews from critics, as it holds an 8% rating on Rotten Tomatoes, based on 36 reviews.


document_title: List of countries by population (United Nations)

question_text: top 3 largest countries in the world population

text: List[edit]

text:
Countries and areas ranked by population in 2017

Rank

Country or area

UN continentalregion[2]

UN statisticalregion[2]

Population(1 July 2016)[3]

Population(1 July 2017)[3]

Change

—

World
—
—
7,466,964,280

7,550,262,101

+1.1%

1

 China[a]
Asia
Eastern Asia
1,403,500,365

1,409,517,397

+0.4%

2

 India
Asia
Southern Asia
1,324,171,354

1,339,180,127

+1.1%

3

 United States
Americas
Northern America
322,179,605

324,459,463

+0.7%

4

 Indonesia
Asia
South-eastern Asia
261,115,456

263,991,379

+1.1%

5

 Brazil
Americas
South America
207,652,865

209,288,278

+0.8%

6

 Pakistan
Asia
Southern Asia
193,203,476

197,015,955

+2.0%

7

 Nigeria
Africa
Western Africa
185,989,640

190,886,311

+2.6%

8

 Bangladesh
Asia
Southern Asia
162,951,560

164,669,751

+1.1%

9

 Russia
Europe
Eastern Europe
146,864,513

146,989,754

+0.1%

10

 Mexico
Americas
Central America
127,540,423

129,163,276

+1.3%

11

 Japan
Asia
Eastern Asia
127,748,513

127,484,450

3000793294658545260♠−0.2%

12

 Ethiopia
Africa
Eastern Africa
102,403,196

104,957,438

+2.5%

13

 Philippines
Asia
South-eastern Asia
103,320,222

104,918,090

+1.5%

14

 Egypt
Africa
Northern Africa
95,688,681

97,553,151

+1.9%

15

 Vietnam
Asia
South-eastern Asia
94,569,072

95,540,800

+1.0%

16

 Germany
Europe
Western Europe
81,914,672

82,114,224

+0.2%

17

 Democratic Republic of the Congo
Africa
Middle Africa
78,736,153

81,339,988

+3.3%

18

 Iran
Asia
Southern Asia
80,277,428

81,162,788

+1.1%

19

 Turkey
Asia
Western Asia
79,512,426

80,745,020

+1.6%

20

 Thailand
Asia
South-eastern Asia
68,863,514

69,037,513

+0.3%

21

 United Kingdom
Europe
Northern Europe
65,788,574

66,181,585

+0.6%

22

 France[b]
Europe
Western Europe
64,720,690

64,979,548

+0.4%

23

 Italy
Europe
Southern Europe
59,429,938

59,359,900

3000882150306130220♠−0.1%

24

 Tanzania[c]
Africa
Eastern Africa
55,572,201

57,310,019

+3.1%

25

 South Africa
Africa
Southern Africa
56,015,473

56,717,156

+1.3%

26

 Myanmar
Asia
South-eastern Asia
52,885,223

53,370,609

+0.9%

27

 South Korea
Asia
Eastern Asia
50,791,919

50,982,212

+0.4%

28

 Colombia
Americas
South America
48,653,419

49,065,615

+0.8%

29

 Kenya
Africa
Eastern Africa
48,461,567

49,699,862

+2.6%

30

 Spain[d]
Europe
Southern Europe
46,347,576

46,354,321

5000000000000000000♠0.0%

31

 Argentina
Americas
South America
43,847,430

44,271,041

+1.0%

32

 Ukraine[e]
Europe
Eastern Europe
44,438,625

44,222,947

3000514660950918270♠−0.5%

33

 Uganda
Africa
Eastern Africa
41,487,965

42,862,958

+3.3%

34

 Algeria
Africa
Northern Africa
40,606,052

41,318,142

+1.8%

35

 Sudan
Africa
Northern Africa
39,578,828

40,533,330

+2.4%

36

 Iraq
Asia
Western Asia
37,202,572

38,274,618

+2.9%

37

 Poland
Europe
Eastern Europe
38,224,410

38,170,712

3000859519087410380♠−0.1%

38

 Canada
Americas
Northern America
36,289,822

36,624,199

+0.9%

39

 Morocco
Africa
Northern Africa
35,276,786

35,739,580

+1.3%

40

 Afghanistan
Asia
Southern Asia
34,656,032

35,530,081

+2.5%

41

 Saudi Arabia
Asia
Western Asia
32,275,687

32,938,213

+2.1%

42

 Peru
Americas
South America
31,773,839

32,165,485

+1.2%

43

 Venezuela
Americas
South America
31,568,179

31,977,065

+1.3%

44

 Uzbekistan
Asia
Central Asia
31,446,795

31,910,641

+1.5%

45

 Malaysia[f]
Asia
South-eastern Asia
31,187,265

31,624,264

+1.4%

46

 Angola
Africa
Middle Africa
28,813,463

29,784,193

+3.4%

47

 Mozambique
Africa
Eastern Africa
28,829,476

29,668,834

+2.9%

48

   Nepal
Asia
Southern Asia
28,982,771

29,304,998

+1.1%

49

 Ghana
Africa
Western Africa
28,206,728

28,833,629

+2.2%

50

 Yemen
Asia
Western Asia
27,584,213

28,250,420

+2.4%

51

 Madagascar
Africa
Eastern Africa
24,894,551

25,570,895

+2.7%

52

 North Korea
Asia
Eastern Asia
25,368,620

25,490,965

+0.5%

53

 Australia[g]
Oceania
Australia and New Zealand
24,125,848

24,450,561

+1.3%

54

 Ivory Coast
Africa
Western Africa
23,695,919

24,294,750

+2.5%

55

 Cameroon
Africa
Middle Africa
23,439,189

24,053,727

+2.6%

56

 Taiwan[h]
Asia
Eastern Asia
23,556,706

23,626,456

+0.3%

57

 Niger
Africa
Western Africa
20,672,987

21,477,348

+3.9%

58

 Sri Lanka
Asia
Southern Asia
20,798,492

20,876,917

+0.4%

59

 Romania
Europe
Eastern Europe
19,778,083

19,679,306

3000500573437779580♠−0.5%

60

 Burkina Faso
Africa
Western Africa
18,646,433

19,193,382

+2.9%

61

 Malawi
Africa
Eastern Africa
18,091,575

18,622,104

+2.9%

62

 Mali
Africa
Western Africa
17,994,837

18,541,980

+3.0%

63

 Syria
Asia
Western Asia
18,430,453

18,269,868

3000128697487793700♠−0.9%

64

 Kazakhstan
Asia
Central Asia
17,987,736

18,204,499

+1.2%

65

 Chile
Americas
South America
17,909,754

18,054,726

+0.8%

66

 Zambia
Africa
Eastern Africa
16,591,390

17,094,130

+3.0%

67

 Netherlands
Europe
Western Europe
16,987,330

17,035,938

+0.3%

68

 Guatemala
Americas
Central America
16,582,469

16,913,503

+2.0%

69

 Ecuador
Americas
South America
16,385,068

16,624,858

+1.5%

70

 Zimbabwe
Africa
Eastern Africa
16,150,362

16,529,904

+2.4%

71

 Cambodia
Asia
South-eastern Asia
15,762,370

16,005,373

+1.5%

72

 Senegal
Africa
Western Africa
15,411,614

15,850,567

+2.8%

73

 Chad
Africa
Middle Africa
14,452,543

14,899,994

+3.1%

74

 Somalia
Africa
Eastern Africa
14,317,996

14,742,523

+3.0%

75

 Guinea
Africa
Western Africa
12,395,924

12,717,176

+2.6%

76

 South Sudan
Africa
Eastern Africa
12,230,730

12,575,714

+2.8%

77

 Rwanda
Africa
Eastern Africa
11,917,508

12,208,407

+2.4%

78

 Tunisia
Africa
Northern Africa
11,403,248

11,532,127

+1.1%

79

 Cuba
Americas
Caribbean
11,475,982

11,484,636

+0.1%

80

 Belgium
Europe
Western Europe
11,358,379

11,429,336

+0.6%

81

 Benin
Africa
Western Africa
10,872,298

11,175,692

+2.8%

82

 Greece
Europe
Southern Europe
11,183,716

11,159,773

3000785911945546550♠−0.2%

83

 Bolivia
Americas
South America
10,887,882

11,051,600

+1.5%

84

 Haiti
Americas
Caribbean
10,847,334

10,981,229

+1.2%

85

 Burundi
Africa
Eastern Africa
10,524,117

10,864,245

+3.2%

86

 Dominican Republic
Americas
Caribbean
10,648,791

10,766,998

+1.1%

87

 Czech Republic
Europe
Eastern Europe
10,610,947

10,618,303

+0.1%

88

 Portugal
Europe
Southern Europe
10,371,627

10,329,506

3000593882425582789♠−0.4%

89

 Sweden
Europe
Northern Europe
9,837,533

9,910,701

+0.7%

90

 Azerbaijan[i]
Asia
Western Asia
9,725,376

9,827,589

+1.1%

91

 Hungary
Europe
Eastern Europe
9,753,281

9,721,559

3000674755602755630♠−0.3%

92

 Jordan
Asia
Western Asia
9,455,802

9,702,353

+2.6%

93

 Belarus
Europe
Eastern Europe
9,480,042

9,468,338

3000876540631360070♠−0.1%

94

 United Arab Emirates
Asia
Western Asia
9,269,612

9,400,145

+1.4%

95

 Honduras
Americas
Central America
9,112,867

9,265,067

+1.7%

96

 Tajikistan
Asia
Central Asia
8,734,951

8,921,343

+2.1%

97

 Serbia[j]
Europe
Southern Europe
8,820,083

8,790,574

3000665433987412590♠−0.3%

98

 Austria
Europe
Western Europe
8,712,137

8,735,453

+0.3%

99

  Switzerland
Europe
Western Europe
8,401,739

8,476,005

+0.9%

100

 Israel
Asia
Western Asia
8,191,828

8,321,570

+1.6%

101

 Papua New Guinea
Oceania
Melanesia
8,084,991

8,251,162

+2.1%

102

 Togo
Africa
Western Africa
7,606,374

7,797,694

+2.5%

103

 Sierra Leone
Africa
Western Africa
7,396,190

7,557,212

+2.2%

104

 Hong Kong
Asia
Eastern Asia
7,302,843

7,364,883

+0.8%

105

 Bulgaria
Europe
Eastern Europe
7,131,494

7,084,571

3000342031277036759♠−0.7%

106

 Laos
Asia
South-eastern Asia
6,758,353

6,858,160

+1.5%

107

 Paraguay
Americas
South America
6,725,308

6,811,297

+1.3%

108

 El Salvador
Americas
Central America
6,344,722

6,377,853

+0.5%

109

 Libya
Africa
Northern Africa
6,293,253

6,374,616

+1.3%

110

 Nicaragua
Americas
Central America
6,149,928

6,217,581

+1.1%

111

 Lebanon
Asia
Western Asia
6,006,668

6,082,357

+1.3%

112

 Kyrgyzstan
Asia
Central Asia
5,955,734

6,045,117

+1.5%

113

 Turkmenistan
Asia
Central Asia
5,662,544

5,758,075

+1.7%

114

 Denmark
Europe
Northern Europe
5,711,870

5,733,551

+0.4%

115

 Singapore
Asia
South-eastern Asia
5,622,455

5,708,844

+1.5%

116

 Finland[k]
Europe
Northern Europe
5,503,132

5,523,231

+0.4%

117

 Slovakia
Europe
Eastern Europe
5,444,218

5,447,662

+0.1%

118

 Norway[l]
Europe
Northern Europe
5,254,694

5,305,383

+1.0%

119

 Congo
Africa
Middle Africa
5,125,821

5,260,750

+2.6%

120

 Eritrea
Africa
Eastern Africa
4,954,645

5,068,831

+2.3%

121

 Palestine[m]
Asia
Western Asia
4,790,705

4,920,724

+2.7%

122

 Costa Rica
Americas
Central America
4,857,274

4,905,769

+1.0%

123

 Ireland
Europe
Northern Europe
4,726,078

4,761,657

+0.8%

124

 Liberia
Africa
Western Africa
4,613,823

4,731,906

+2.6%

125

 New Zealand
Oceania
Australia and New Zealand
4,660,833

4,705,818

+1.0%

126

 Central African Republic
Africa
Middle Africa
4,594,621

4,659,080

+1.4%

127

 Oman
Asia
Western Asia
4,424,762

4,636,262

+4.8%

128

 Mauritania
Africa
Western Africa
4,301,018

4,420,184

+2.8%

129

 Croatia
Europe
Southern Europe
4,213,265

4,189,353

3000432459149851719♠−0.6%

130

 Kuwait
Asia
Western Asia
4,052,584

4,136,528

+2.1%

131

 Panama
Americas
Central America
4,034,119

4,098,587

+1.6%

132

 Moldova[n]
Europe
Eastern Europe
4,059,608

4,051,212

3000793182001809040♠−0.2%

133

 Georgia[o]
Asia
Western Asia
3,925,405

3,912,061

3000660060554261280♠−0.3%

134

 Puerto Rico
Americas
Caribbean
3,667,903

3,663,131

3000869898413344080♠−0.1%

135

 Bosnia and Herzegovina
Europe
Southern Europe
3,516,816

3,507,017

3000721367282223460♠−0.3%

136

 Uruguay
Americas
South America
3,444,006

3,456,750

+0.4%

137

 Mongolia
Asia
Eastern Asia
3,027,398

3,075,647

+1.6%

138

 Armenia
Asia
Western Asia
2,924,816

2,930,450

+0.2%

139

 Albania
Europe
Southern Europe
2,926,348

2,930,187

+0.1%

140

 Jamaica
Americas
Caribbean
2,881,355

2,890,299

+0.3%

141

 Lithuania
Europe
Northern Europe
2,908,249

2,890,297

3000382721355702350♠−0.6%

142

 Qatar
Asia
Western Asia
2,569,804

2,639,211

+2.7%

143

 Namibia
Africa
Southern Africa
2,479,713

2,533,794

+2.2%

144

 Botswana
Africa
Southern Africa
2,250,260

2,291,661

+1.8%

145

 Lesotho
Africa
Southern Africa
2,203,821

2,233,339

+1.3%

146

 The Gambia
Africa
Western Africa
2,038,501

2,100,568

+3.0%

147

 Republic of Macedonia
Europe
Southern Europe
2,081,206

2,083,160

+0.1%

148

 Slovenia
Europe
Southern Europe
2,077,862

2,079,976

+0.1%

149

 Gabon
Africa
Middle Africa
1,979,786

2,025,137

+2.3%

150

 Latvia
Europe
Northern Europe
1,970,530

1,949,670

2999894140155186680♠−1.1%

151

 Guinea-Bissau
Africa
Western Africa
1,815,698

1,861,283

+2.5%

152

 Bahrain
Asia
Western Asia
1,425,171

1,492,584

+4.7%

153

 Trinidad and Tobago
Americas
Caribbean
1,364,962

1,369,125

+0.3%

154

 Swaziland
Africa
Southern Africa
1,343,098

1,367,254

+1.8%

155

 Estonia
Europe
Northern Europe
1,312,442

1,309,632

3000785895300516140♠−0.2%

156

 East Timor
Asia
South-eastern Asia
1,268,671

1,296,311

+2.2%

157

 Equatorial Guinea
Africa
Middle Africa
1,221,490

1,267,689

+3.8%

158

 Mauritius[p]
Africa
Eastern Africa
1,262,132

1,265,138

+0.2%

159

 Cyprus[q]
Asia
Western Asia
1,170,125

1,179,551

+0.8%

160

 Djibouti
Africa
Eastern Africa
942,333

956,985

+1.6%

161

 Fiji
Oceania
Melanesia
898,760

905,502

+0.8%

162

 Réunion
Africa
Eastern Africa
869,925

876,562

+0.8%

163

 Comoros
Africa
Eastern Africa
795,601

813,912

+2.3%

164

 Bhutan
Asia
Southern Asia
797,765

807,610

+1.2%

165

 Guyana
Americas
South America
773,303

777,859

+0.6%

166

 Montenegro
Europe
Southern Europe
628,615

628,960

+0.1%

167

 Macau
Asia
Eastern Asia
612,167

622,567

+1.7%

168

 Solomon Islands
Oceania
Melanesia
599,419

611,343

+2.0%

169

 Luxembourg
Europe
Western Europe
575,747

583,455

+1.3%

170

 Suriname
Americas
South America
558,368

563,402

+0.9%

171

 Western Sahara
Africa
Northern Africa
538,755

552,628

+2.6%

172

 Cape Verde
Africa
Western Africa
539,560

546,388

+1.3%

173

 Guadeloupe[r]
Americas
Caribbean
449,975

449,568

3001095505305850340♠−0.1%

174

 Maldives
Asia
Southern Asia
427,756

436,330

+2.0%

175

 Malta
Europe
Southern Europe
429,362

430,835

+0.3%

176

 Brunei
Asia
South-eastern Asia
423,196

428,697

+1.3%

177

 Bahamas
Americas
Caribbean
391,232

395,361

+1.1%

178

 Martinique
Americas
Caribbean
385,103

384,896

3001462481465997370♠−0.1%

179

 Belize
Americas
Central America
366,954

374,681

+2.1%

180

 Iceland
Europe
Northern Europe
332,474

335,025

+0.8%

181

 Barbados
Americas
Caribbean
284,996

285,719

+0.3%

182

 French Polynesia
Oceania
Polynesia
280,208

283,007

+1.0%

183

 French Guiana
Americas
South America
275,713

282,731

+2.5%

184

 New Caledonia
Oceania
Melanesia
272,677

276,255

+1.3%

185

 Vanuatu
Oceania
Melanesia
270,402

276,244

+2.2%

186

 Mayotte
Africa
Eastern Africa
246,489

253,045

+2.7%

187

 Sao Tome and Principe
Africa
Middle Africa
199,910

204,327

+2.2%

188

 Samoa
Oceania
Polynesia
195,125

196,440

+0.7%

189

 Saint Lucia
Americas
Caribbean
178,015

178,844

+0.5%

190

 Guernsey and  Jersey
Europe
Northern Europe
164,541

165,314

+0.5%

191

 Guam
Oceania
Micronesia
162,896

164,229

+0.8%

192

 Curaçao
Americas
Caribbean
159,371

160,539

+0.7%

193

 Kiribati
Oceania
Micronesia
114,395

116,398

+1.8%

194

 Saint Vincent and the Grenadines
Americas
Caribbean
109,643

109,897

+0.2%

195

 Tonga
Oceania
Polynesia
107,122

108,020

+0.8%

196

 Grenada
Americas
Caribbean
107,317

107,825

+0.5%

197

 Federated States of Micronesia
Oceania
Micronesia
104,937

105,544

+0.6%

198

 Aruba
Americas
Caribbean
104,822

105,264

+0.4%

199

 United States Virgin Islands
Americas
Caribbean
104,913

104,901

5000000000000000000♠0.0%

200

 Antigua and Barbuda
Americas
Caribbean
100,963

102,012

+1.0%

201

 Seychelles
Africa
Eastern Africa
94,228

94,737

+0.5%

202

 Isle of Man
Europe
Northern Europe
83,737

84,287

+0.7%

203

 Andorra
Europe
Southern Europe
77,281

76,965

3000591102599604040♠−0.4%

204

 Dominica
Americas
Caribbean
73,543

73,925

+0.5%

205

 Cayman Islands
Americas
Caribbean
60,765

61,559

+1.3%

206

 Bermuda
Americas
Northern America
61,666

61,349

3000485940388544740♠−0.5%

207

 Greenland
Americas
Northern America
56,412

56,480

+0.1%

208

 American Samoa
Oceania
Polynesia
55,599

55,641

+0.1%

209

 Saint Kitts and Nevis
Americas
Caribbean
54,821

55,345

+1.0%

210

 Northern Mariana Islands
Oceania
Micronesia
55,023

55,144

+0.2%

211

 Marshall Islands
Oceania
Micronesia
53,066

53,127

+0.1%

212

 Faroe Islands
Europe
Northern Europe
49,117

49,290

+0.4%

213

 Sint Maarten
Americas
Caribbean
39,537

40,120

+1.5%

214

 Monaco
Europe
Western Europe
38,499

38,695

+0.5%

215

 Liechtenstein
Europe
Western Europe
37,666

37,922

+0.7%

216

 Turks and Caicos Islands
Americas
Caribbean
34,900

35,446

+1.6%

217

 Gibraltar
Europe
Southern Europe
34,408

34,571

+0.5%

218

 San Marino
Europe
Southern Europe
33,203

33,400

+0.6%

219

 British Virgin Islands
Americas
Caribbean
30,661

31,196

+1.7%

220

 Caribbean Netherlands[s]
Americas
Caribbean
25,019

25,398

+1.5%

221

 Palau
Oceania
Micronesia
21,503

21,729

+1.1%

222

 Cook Islands
Oceania
Polynesia
17,379

17,380

5000000000000000000♠0.0%

223

 Anguilla
Americas
Caribbean
14,764

14,909

+1.0%

224

 Wallis and Futuna
Oceania
Polynesia
11,899

11,773

2999894108748634340♠−1.1%

225

 Nauru
Oceania
Micronesia
11,347

11,359

+0.1%

226

 Tuvalu
Oceania
Polynesia
11,097

11,192

+0.9%

227

 Saint Pierre and Miquelon
Americas
Northern America
6,305

6,320

+0.2%

228

 Montserrat
Americas
Caribbean
5,152

5,177

+0.5%

229

 Saint Helena, Ascension and Tristan da Cunha
Africa
Western Africa
4,035

4,049

+0.3%

230

 Falkland Islands
Americas
South America
2,910

2,910

5000000000000000000♠0.0%

231

 Niue
Oceania
Polynesia
1,624

1,618

3000630541871921189♠−0.4%

232

 Tokelau
Oceania
Polynesia
1,282

1,300

+1.4%

233

  Vatican City[t]
Europe
Southern Europe
801

792

2999887640449438199♠−1.1%


document_title: Conservation of energy

question_text: who devised the law of conservation of energy

text: Conservation of energy

text: History[edit]

text: This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2015) (Learn how and when to remove this template message)

text: Ancient philosophers as far back as Thales of Miletus c. 550 BCE had inklings of the conservation of some underlying substance of which everything is made. However, there is no particular reason to identify this with what we know today as "mass-energy" (for example, Thales thought it was water). Empedocles (490–430 BCE) wrote that in his universal system, composed of four roots (earth, air, water, fire), "nothing comes to be or perishes";[8] instead, these elements suffer continual rearrangement.

text: In 1605, Simon Stevinus was able to solve a number of problems in statics based on the principle that perpetual motion was impossible.

text: In 1638, Galileo published his analysis of several situations—including the celebrated "interrupted pendulum"—which can be described (in modern language) as conservatively converting potential energy to kinetic energy and back again. Essentially, he pointed out that the height a moving body rises is equal to the height from which it falls, and used this observation to infer the idea of inertia. The remarkable aspect of this observation is that the height to which a moving body ascends on a frictionless surface does not depend on the shape of the surface.

text: In 1669, Christian Huygens published his laws of collision. Among the quantities he listed as being invariant before and after the collision of bodies were both the sum of their linear momentums as well as the sum of their kinetic energies. However, the difference between elastic and inelastic collision was not understood at the time. This led to the dispute among later researchers as to which of these conserved quantities was the more fundamental. In his Horologium Oscillatorium, he gave a much clearer statement regarding the height of ascent of a moving body, and connected this idea with the impossibility of a perpetual motion. Huygens' study of the dynamics of pendulum motion was based on a single principle: that the center of gravity of a heavy object cannot lift itself.

text: The fact that kinetic energy is scalar, unlike linear momentum which is a vector, and hence easier to work with did not escape the attention of Gottfried Wilhelm Leibniz. It was Leibniz during 1676–1689 who first attempted a mathematical formulation of the kind of energy which is connected with motion (kinetic energy). Using Huygens' work on collision, Leibniz noticed that in many mechanical systems (of several masses, mi each with velocity vi),

text: was conserved so long as the masses did not interact. He called this quantity the vis viva or living force of the system. The principle represents an accurate statement of the approximate conservation of kinetic energy in situations where there is no friction. Many physicists at that time, such as Newton, held that the conservation of momentum, which holds even in systems with friction, as defined by the momentum:

text: was the conserved vis viva. It was later shown that both quantities are conserved simultaneously, given the proper conditions such as an elastic collision.

text: In 1687, Isaac Newton published his Principia, which was organized around the concept of force and momentum. However, the researchers were quick to recognize that the principles set out in the book, while fine for point masses, were not sufficient to tackle the motions of rigid and fluid bodies. Some other principles were also required.

text: The law of conservation of vis viva was championed by the father and son duo, Johann and Daniel Bernoulli. The former enunciated the principle of virtual work as used in statics in its full generality in 1715, while the later based his Hydrodynamica, published in 1738, on this single conservation principle. Daniel's study of loss of vis viva of flowing water led him to formulate the Bernoulli's principle, which relates the loss to be proportional to the change in hydrodynamic pressure. Daniel also formulated the notion of work and efficiency for hydraulic machines; and he gave a kinetic theory of gases, and linked the kinetic energy of gas molecules with the temperature of the gas.

text: This focus on the vis viva by the continental physicists eventually led to the discovery of stationarity principles governing mechanics, such as the D'Alembert's principle and Lagrangian and Hamiltonian formulations of mechanics.

text:
Émilie du Châtelet (1706 – 1749) proposed and tested the hypothesis of the conservation of total energy, as distinct from momentum. Inspired by the theories of Gottfried Leibniz, she repeated and publicized an experiment originally devised by Willem 's Gravesande in 1722 in which balls were dropped from different heights into a sheet of soft clay. Each ball's kinetic energy - as indicated by the quantity of material displaced - was shown to be proportional to the square of the velocity. The deformation of the clay was found to be directly proportional to the height the balls were dropped from, equal to the initial potential energy. Earlier workers, including Newton and Voltaire, had all believed that "energy" (so far as they understood the concept at all) was not distinct from momentum and therefore proportional to velocity. According to this understanding, the deformation of the clay should have been proportional to the square root of the height from which the balls were dropped from. In classical physics the correct formula is

E

k

=

1
2

m

v

2

{\displaystyle E_{k}={\frac {1}{2}}mv^{2}}

, where

E

k

{\displaystyle E_{k}}

 is the kinetic energy of an object,

m

{\displaystyle m}

 its mass and

v

{\displaystyle v}

 its speed. On this basis, Châtelet proposed that energy must always have the same dimensions in any form, which is necessary to be able to relate it in different forms (kinetic, potential, heat…).[9][10]

text: Engineers such as John Smeaton, Peter Ewart, Carl Holtzmann, Gustave-Adolphe Hirn and Marc Seguin recognized that conservation of momentum alone was not adequate for practical calculation and made use of Leibniz's principle. The principle was also championed by some chemists such as William Hyde Wollaston. Academics such as John Playfair were quick to point out that kinetic energy is clearly not conserved. This is obvious to a modern analysis based on the second law of thermodynamics, but in the 18th and 19th centuries the fate of the lost energy was still unknown.

text: Gradually it came to be suspected that the heat inevitably generated by motion under friction was another form of vis viva. In 1783, Antoine Lavoisier and Pierre-Simon Laplace reviewed the two competing theories of vis viva and caloric theory.[11] Count Rumford's 1798 observations of heat generation during the boring of cannons added more weight to the view that mechanical motion could be converted into heat, and (as importantly) that the conversion was quantitative and could be predicted (allowing for a universal conversion constant between kinetic energy and heat). Vis viva then started to be known as energy, after the term was first used in that sense by Thomas Young in 1807.

text: The recalibration of vis viva to

text: which can be understood as converting kinetic energy to work, was largely the result of Gaspard-Gustave Coriolis and Jean-Victor Poncelet over the period 1819–1839. The former called the quantity quantité de travail (quantity of work) and the latter, travail mécanique (mechanical work), and both championed its use in engineering calculation.

text: In a paper Über die Natur der Wärme(German "On the Nature of Heat/Warmth"), published in the Zeitschrift für Physik in 1837, Karl Friedrich Mohr gave one of the earliest general statements of the doctrine of the conservation of energy in the words: "besides the 54 known chemical elements there is in the physical world one agent only, and this is called Kraft [energy or work]. It may appear, according to circumstances, as motion, chemical affinity, cohesion, electricity, light and magnetism; and from any one of these forms it can be transformed into any of the others."

text: Mechanical equivalent of heat[edit]

text: A key stage in the development of the modern conservation principle was the demonstration of the mechanical equivalent of heat. The caloric theory maintained that heat could neither be created nor destroyed, whereas conservation of energy entails the contrary principle that heat and mechanical work are interchangeable.

text: In the middle of the eighteenth century, Mikhail Lomonosov, a Russian scientist, postulated his corpusculo-kinetic theory of heat, which rejected the idea of a caloric. Through the results of empirical studies, Lomonosov came to the conclusion that heat was not transferred through the particles of the caloric fluid.

text: In 1798, Count Rumford (Benjamin Thompson) performed measurements of the frictional heat generated in boring cannons, and developed the idea that heat is a form of kinetic energy; his measurements refuted caloric theory, but were imprecise enough to leave room for doubt.

text: The mechanical equivalence principle was first stated in its modern form by the German surgeon Julius Robert von Mayer in 1842.[12] Mayer reached his conclusion on a voyage to the Dutch East Indies, where he found that his patients' blood was a deeper red because they were consuming less oxygen, and therefore less energy, to maintain their body temperature in the hotter climate. He discovered that heat and mechanical work were both forms of energy and in 1845, after improving his knowledge of physics, he published a monograph that stated a quantitative relationship between them.[13]

text: Meanwhile, in 1843, James Prescott Joule independently discovered the mechanical equivalent in a series of experiments. In the most famous, now called the "Joule apparatus", a descending weight attached to a string caused a paddle immersed in water to rotate. He showed that the gravitational potential energy lost by the weight in descending was equal to the internal energy gained by the water through friction with the paddle.

text: Over the period 1840–1843, similar work was carried out by engineer Ludwig A. Colding, although it was little known outside his native Denmark.

text: Both Joule's and Mayer's work suffered from resistance and neglect but it was Joule's that eventually drew the wider recognition.

text: In 1844, William Robert Grove postulated a relationship between mechanics, heat, light, electricity and magnetism by treating them all as manifestations of a single "force" (energy in modern terms). In 1846, Grove published his theories in his book The Correlation of Physical Forces.[14] In 1847, drawing on the earlier work of Joule, Sadi Carnot and Émile Clapeyron, Hermann von Helmholtz arrived at conclusions similar to Grove's and published his theories in his book Über die Erhaltung der Kraft (On the Conservation of Force, 1847).[15] The general modern acceptance of the principle stems from this publication.

text: In 1850, William Rankine first used the phrase the law of the conservation of energy for the principle.[16]

text: In 1877, Peter Guthrie Tait claimed that the principle originated with Sir Isaac Newton, based on a creative reading of propositions 40 and 41 of the Philosophiae Naturalis Principia Mathematica. This is now regarded as an example of Whig history.[17]

text: Mass–energy equivalence[edit]

text: Matter is composed of such things as atoms, electrons, neutrons, and protons. It has intrinsic or rest mass. In the limited range of recognized experience of the nineteenth century it was found that such rest mass is conserved. Einstein's 1905 theory of special relativity showed that it corresponds to an equivalent amount of rest energy. This means that it can be converted to or from equivalent amounts of other (non-material) forms of energy, for example kinetic energy, potential energy, and electromagnetic radiant energy. When this happens, as recognized in twentieth century experience, rest mass is not conserved, unlike the total mass or total energy. All forms of energy contribute to the total mass and total energy.

text: For example, an electron and a positron each have rest mass. They can perish together, converting their combined rest energy into photons having electromagnetic radiant energy, but no rest mass. If this occurs within an isolated system that does not release the photons or their energy into the external surroundings, then neither the total mass nor the total energy of the system will change. The produced electromagnetic radiant energy contributes just as much to the inertia (and to any weight) of the system as did the rest mass of the electron and positron before their demise. Likewise, non-material forms of energy can perish into matter, which has rest mass.

text: Thus, conservation of energy (total, including material or rest energy), and conservation of mass (total, not just rest), each still holds as an (equivalent) law. In the 18th century these had appeared as two seemingly-distinct laws.

text: Conservation of energy in beta decay[edit]

text: The discovery in 1911 that electrons emitted in beta decay have a continuous rather than a discrete spectrum appeared to contradict conservation of energy, under the then-current assumption that beta decay is the simple emission of an electron from a nucleus.[18][19] This problem was eventually resolved in 1933 by Enrico Fermi who proposed the correct description of beta-decay as the emission of both an electron and an antineutrino, which carries away the apparently missing energy.[20][21]

text: First law of thermodynamics[edit]

text: For a closed thermodynamic system, the first law of thermodynamics may be stated as:

text:
where

δ
Q

{\displaystyle \delta Q}

 is the quantity of energy added to the system by a heating process,

δ
W

{\displaystyle \delta W}

 is the quantity of energy lost by the system due to work done by the system on its surroundings and

d

U

{\displaystyle \mathrm {d} U}

 is the change in the internal energy of the system.

text:
The δ's before the heat and work terms are used to indicate that they describe an increment of energy which is to be interpreted somewhat differently than the

d

U

{\displaystyle \mathrm {d} U}

 increment of internal energy (see Inexact differential). Work and heat refer to kinds of process which add or subtract energy to or from a system, while the internal energy

U

{\displaystyle U}

 is a property of a particular state of the system when it is in unchanging thermodynamic equilibrium. Thus the term "heat energy" for

δ
Q

{\displaystyle \delta Q}

 means "that amount of energy added as the result of heating" rather than referring to a particular form of energy. Likewise, the term "work energy" for

δ
W

{\displaystyle \delta W}

 means "that amount of energy lost as the result of work". Thus one can state the amount of internal energy possessed by a thermodynamic system that one knows is presently in a given state, but one cannot tell, just from knowledge of the given present state, how much energy has in the past flowed into or out of the system as a result of its being heated or cooled, nor as the result of work being performed on or by the system.

text: Entropy is a function of the state of a system which tells of limitations of the possibility of conversion of heat into work.

text: For a simple compressible system, the work performed by the system may be written:

text:
where

P

{\displaystyle P}

 is the pressure and

d
V

{\displaystyle dV}

 is a small change in the volume of the system, each of which are system variables. In the fictive case in which the process is idealized and infinitely slow, so as to be called quasi-static, and regarded as reversible, the heat being transferred from a source with temperature infinitesimally above the system temperature, then the heat energy may be written

text:
where

T

{\displaystyle T}

 is the temperature and

d

S

{\displaystyle \mathrm {d} S}

 is a small change in the entropy of the system. Temperature and entropy are variables of state of a system.

text: If an open system (in which mass may be exchanged with the environment) has several walls such that the mass transfer is through rigid walls separate from the heat and work transfers, then the first law may be written:[22]

text:
where

d
M

{\displaystyle dM}

 is the added mass and

u
′

{\displaystyle u'}

 is the internal energy per unit mass of the added mass, measured in the surroundings before the process.

text: Noether's theorem[edit]

text: The conservation of energy is a common feature in many physical theories. From a mathematical point of view it is understood as a consequence of Noether's theorem, developed by Emmy Noether in 1915 and first published in 1918. The theorem states every continuous symmetry of a physical theory has an associated conserved quantity; if the theory's symmetry is time invariance then the conserved quantity is called "energy". The energy conservation law is a consequence of the shift symmetry of time; energy conservation is implied by the empirical fact that the laws of physics do not change with time itself. Philosophically this can be stated as "nothing depends on time per se". In other words, if the physical system is invariant under the continuous symmetry of time translation then its energy (which is canonical conjugate quantity to time) is conserved. Conversely, systems which are not invariant under shifts in time (an example, systems with time dependent potential energy) do not exhibit conservation of energy – unless we consider them to exchange energy with another, external system so that the theory of the enlarged system becomes time invariant again. Conservation of energy for finite systems is valid in such physical theories as special relativity and quantum theory (including QED) in the flat space-time.

text: Relativity[edit]

text: With the discovery of special relativity by Henri Poincaré and Albert Einstein, energy was proposed to be one component of an energy-momentum 4-vector. Each of the four components (one of energy and three of momentum) of this vector is separately conserved across time, in any closed system, as seen from any given inertial reference frame. Also conserved is the vector length (Minkowski norm), which is the rest mass for single particles, and the invariant mass for systems of particles (where momenta and energy are separately summed before the length is calculated—see the article on invariant mass).

text:
The relativistic energy of a single massive particle contains a term related to its rest mass in addition to its kinetic energy of motion. In the limit of zero kinetic energy (or equivalently in the rest frame) of a massive particle, or else in the center of momentum frame for objects or systems which retain kinetic energy, the total energy of particle or object (including internal kinetic energy in systems) is related to its rest mass or its invariant mass via the famous equation

E
=
m

c

2

{\displaystyle E=mc^{2}}

.

text: Thus, the rule of conservation of energy over time in special relativity continues to hold, so long as the reference frame of the observer is unchanged. This applies to the total energy of systems, although different observers disagree as to the energy value. Also conserved, and invariant to all observers, is the invariant mass, which is the minimal system mass and energy that can be seen by any observer, and which is defined by the energy–momentum relation.

text: In general relativity, energy–momentum conservation is not well-defined except in certain special cases. Energy-momentum is typically expressed with the aid of a stress–energy–momentum pseudotensor. However, since pseudotensors are not tensors, they do not transform cleanly between reference frames. If the metric under consideration is static (that is, does not change with time) or asymptotically flat (that is, at an infinite distance away spacetime looks empty), then energy conservation holds without major pitfalls. In practice, some metrics such as the Friedmann–Lemaître–Robertson–Walker metric do not satisfy these constraints and energy conservation is not well defined.[23] The theory of general relativity leaves open the question of whether there is a conservation of energy for the entire universe.

text: Quantum theory[edit]

text: In quantum mechanics, energy of a quantum system is described by a self-adjoint (or Hermitian) operator called the Hamiltonian, which acts on the Hilbert space (or a space of wave functions) of the system. If the Hamiltonian is a time-independent operator, emergence probability of the measurement result does not change in time over the evolution of the system. Thus the expectation value of energy is also time independent. The local energy conservation in quantum field theory is ensured by the quantum Noether's theorem for energy-momentum tensor operator. Note that due to the lack of the (universal) time operator in quantum theory, the uncertainty relations for time and energy are not fundamental in contrast to the position-momentum uncertainty principle, and merely holds in specific cases (see Uncertainty principle). Energy at each fixed time can in principle be exactly measured without any trade-off in precision forced by the time-energy uncertainty relations. Thus the conservation of energy in time is a well defined concept even in quantum mechanics.