Homework 22 Solutions

Homework 22 Solutions - lim (kl9356) Homework 22 Weathers...

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lim (kl9356) – Homework 22 – Weathers – (17104) 1 This print-out should have 18 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points A square hole 10 . 5 cm along each side is cut in a sheet oF copper. Calculate the change in the area oF this hole iF the temperature oF the sheet is increased by 76 K. Correct answer: 0 . 284886 cm 2 . Explanation: Given : L = 10 . 5 cm and Δ T = 76 K . Each side oF the hole expands linearly by Δ L = Δ T . The area, thereFore expands by Δ A = ( L + Δ L ) 2 - A . Since Δ L is much smaller than L we should keep only the linear term in Δ L , so Δ A = 2 L Δ L = 2 αA Δ T = 2 b 1 . 7 × 10 5 ( C) 1 B ( 110 . 25 cm 2 ) (76 K) = 0 . 284886 cm 2 002 (part 1 oF 2) 10.0 points At 9 C, an aluminum ring has an inner diam- eter oF 3 cm and a brass rod has a diameter oF 3 . 06 cm. IF the temperature coe±cient oF expansion For brass is α b = 1 . 9 × 10 5 ( C) 1 and the temperature coe±cient oF expansion For alu- minum is α a = 2 . 4 × 10 5 ( C) 1 , to what temperature must the ring be heated so that it will just slip over the rod? Correct answer: 842 . 333 C. Explanation: Given : T 0 = 9 C , d a = 3 cm , d b = 3 . 06 cm , α b = 1 . 9 × 10 5 ( C) 1 , and α a = 2 . 4 × 10 5 ( C) 1 . The new length will be d b = d a (1 + α Δ T ) d b = d a + d a α Δ T T 1 = T 0 + Δ T = T 0 + d b - d a d a α a = 9 C + 3 . 06 cm - 3 cm (3 cm)(2 . 4 × 10 5 ( C) 1 ) = 842 . 333 C . 003 (part 2 oF 2) 10.0 points To what temperature must both be heated so that the ring just slips over the rod? Correct answer: 4338 C. Explanation: We need L Al = L brass For some Δ T . Using the same law, L 0 Al (1 + α a Δ T ) = L 0 brass (1 + α b Δ T ) d a + d a α a Δ T = d b + d b α b Δ T Δ T = T 0 + d b - d a α a d a - α b d b α a d a - α b d b = b 2 . 4 × 10 5 ( C) 1 B (3 cm) - b 1 . 9 × 10 5 ( C) 1 B (3 . 06 cm) = 1 . 386 × 10 5 m / C so Δ T = T 2 - T 0 T 2 = T 0 + Δ T = T 0 + d b - d a α a d a - α b d b = 9 C + 3 . 06 cm - 3 cm 1 . 386 × 10 5 m / C = 4338 C . 004 10.0 points
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lim (kl9356) – Homework 22 – Weathers – (17104) 2 2 mole of xenon gas at 37 C occupies 0 . 294 m 3 . What is the pressure exerted by the Xe
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This note was uploaded on 09/07/2010 for the course PHYS 1710 taught by Professor Weathers during the Fall '08 term at North Texas.

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Homework 22 Solutions - lim (kl9356) Homework 22 Weathers...

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