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Unformatted text preview: poincy (cp26467) Homework 1 williams (999949) 1 This printout should have 22 questions. Multiplechoice questions may continue on the next column or page find all choices before answering. 001 10.0 points At what Fahrenheit temperature are the Cel sius and Fahrenheit temperatures numerically equal? Correct answer: 40 F. Explanation: T F = 9 5 T C + 32 , so x = 9 5 x + 32 4 5 x = 32 x = 5 4 (32) = 40 , so 40 C = 40 F. 002 10.0 points The temperature of a 2 . 6 m copper pipe is raised from 72 C to 977 C. What is its change in length? Assume the coefficient of linear expansion for copper is 1 . 7 10 5 ( C) 1 . Correct answer: 0 . 040001 m. Explanation: Given : L 1 = 2 . 6 m , T 1 = 72 C , T 2 = 977 C , and = 1 . 7 10 5 ( C) 1 . The change in length is given by L = L 1 T = L 1 ( T 2 T 1 ) = bracketleftbig 1 . 7 10 5 ( C) 1 bracketrightbig (2 . 6 m) (977 C 72 C) = . 040001 m 003 10.0 points A gold ring has an inner diameter of 0 . 9754 cm at a temperature of 10 C. Determine its inner diameter at 120 C. (The coefficient of linear expansion is 1 . 42 10 5 ( C) 1 .) Correct answer: 0 . 976924 cm. Explanation: Given : L 1 = 0 . 9754 cm , T 1 = 10 C , T 2 = 120 C , and = 1 . 42 10 5 ( C) 1 . The diameter expands by L = L 1 T = L 1 ( T 2 T 1 ) = bracketleftbig 1 . 42 10 5 ( C) 1 bracketrightbig (0 . 9754 cm) (120 C 10 C) = 0 . 00152357 cm . and L 2 = L 1 + L = 0 . 9754 cm + 0 . 00152357 cm = . 976924 cm . 004 10.0 points A square hole 6 . 1 cm along each side is cut in a sheet of copper. Find the change in the area of this hole if the temperature of the sheet is increased by 74 K. The coefficient of expasion is 1 . 7 10 5 ( C) 1 . Correct answer: 0 . 0936204 cm 2 . Explanation: Let : L = 6 . 1 cm , T = 74 K , and = 1 . 7 10 5 ( C) 1 . poincy (cp26467) Homework 1 williams (999949) 2 Each side of the hole expands linearly by L = L T , so the area expands by A = ( L + L ) 2 A . Since L is much smaller than L we should keep only the linear term in L , so A = 2 L L = 2 A T = 2 L 2 T = 2 bracketleftbig 1 . 7 10 5 ( C) 1 bracketrightbig ( 37 . 21 cm 2 ) (74 K) = . 0936204 cm 2 . 005 10.0 points A lake contains approximately 1 . 24 10 6 kg of water. What is its heat capacity? The specific heat of water is 1000 cal / kg C....
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 Spring '11
 Williams
 Physics, Work

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