HW2-2011

# HW2-2011 - . (a) What is V 1 ? (b) Changing to p 2 =...

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ECH 152A, Fall 2011, Roland Faller Homework 2, October 3, 2011 Due: October 10, Beginning of Lecture 1. (5 points) An egg which is initially at rest is dropped on a hard surface and breaks. We wait that any temperature change equilibrates. Take the egg as system. (a) What is the sign of W ? (b) What is the sign of Δ E pot ? (c) What is Δ E kin (just before and just after impact)? (d) What is Δ U tot ? (e) What is the sign of Q ? 2. (4 points) Complete the table for a four step cycle of a closed system. Step Δ U [J] Q [J] W [J] 1 2 -450 -6000 2 3 -3300 3 4 -700 350 4 1 5800 12341 -1000 3. (6 points, This problem was on Midterm 1, 2010) Assume you have a perfectly isolated, closed system under reversible and isother- mal conditions where pV 0 . 8 = 5000kJm - 0 . 6 . You start with the system at p 1 = 100 kPa

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Unformatted text preview: . (a) What is V 1 ? (b) Changing to p 2 = 170kPa, what is the work and V 2 ? (c) Redo (a, b) for one mol of ideal gas at 300 K. The gas constant is R = 8 . 31J/(mol K). 4. (3 points) Why can you not cool your kitchen by opening the refrigerator door? Why does it work with an air conditioner? 5. (4 points, This problem was on Midterm 1, 2008) We have a closed system containing an ideal gas ( pV = aT, c v = b ; a,b constants). (a) Calculate the work to triple the pressure from p to 3 p . What is the sign? (b) How much heat is transferred (and which way) in part (a) if T is constant. (c) Now we perform the compression of part (a) under constant internal energy, how does the temperature change?...
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## This note was uploaded on 11/12/2011 for the course ECH 152A taught by Professor Faller during the Fall '09 term at UC Davis.

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HW2-2011 - . (a) What is V 1 ? (b) Changing to p 2 =...

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