Homework 1-solutions

Homework 1-solutions - poincy (cp26467) Homework 1 williams...

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Unformatted text preview: poincy (cp26467) Homework 1 williams (999949) 1 This print-out should have 22 questions. Multiple-choice 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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Homework 1-solutions - poincy (cp26467) Homework 1 williams...

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