Please Note: It may not always be possible to include the necessary special characters, superscripts, subscripts, etc. in e-mail responses to this group of exercises. We suggest that you discuss this matter with your professor/class and decide upon a system for indicating such characters. You may cut/paste some characters and/or Greek letters from Microsoft Word, using the Insert menu. Alternatively, we suggest that you agree upon abbreviations for or spell out symbols, Greek letters, or characters and indicate superscripts and subscripts by using "sup", "sub", or up/down carats.

1			If you leave the refrigerator door open and the refrigerator runs continuously, does the kitchen get colder or warmer? Explain.
2			Why are heat pumps more often used in mild climates than in areas with severely cold winters?
3			The internal energy of a system increases by 400 J while 500 J of work are performed on it. What was the heat flow into or out of the system?
4			A monatomic ideal gas at 27°C undergoes a constant pressure process from A to B and a constant volume process from B to C, as shown in Fig. 15.20a. Find the total work done during these two processes. <a onClick="window.open('/olcweb/cgi/pluginpop.cgi?it=gif::Fig. 15.20::/sites/dl/free/0070524076/57998/fig_020.gif','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif">Fig. 15.20 (4.0K)</a>Fig. 15.20
5			The efficiency of an engine is 0.21. For every 1.00 kJ of heat absorbed by the engine, how much (a) net work is done by it and (b) heat is released by it?
6			The intensity (power per unit area) of the sunlight incident on the Earth's surface, averaged over a 24-h period, is about 0.20 kW/m2. If a solar power plant is to be built with an output capacity of 1.0 × 109 W, how big must the area of the solar energy collectors be for photocells operating at 20.0% efficiency?
7			Calculate the maximum possible efficiency of a heat engine that uses surface lake water at 18.0°C as a source of heat and rejects waste heat to the water 0.100 km below the surface where the temperature is 4.0°C.
8			A heat pump is used to heat a house with an interior temperature of 20.0°C. On a chilly day with an outdoor temperature of -10.0°C, what is the minimum work that the pump requires in order to deliver 1.0 kJ of heat to the house?
9			An ideal refrigerator keeps its contents at 0.0°C and exhausts heat into the kitchen at 40.0°C. For every 1.0 kJ of work done, (a) how much heat is exhausted? (b) How much heat is removed from the contents?
10			List these in order of increasing entropy: (a) 0.5 kg of ice and 0.5 kg of (liquid) water at 0°C; (b) 1 kg of ice at 0°C; (c) 1 kg of (liquid) water at 0°C; (d) 1 kg of water at 20°C.
11			A large block of copper initially at 20.0°C is placed in a vat of hot water (80.0°C). For the first 1.0 J of heat that flows from the water into the block, find (a) the entropy change of the block, (b) the entropy change of the water, and (c) the entropy change of the universe. Note that the temperatures of the block and water are essentially unchanged by the flow of only 1.0 J of heat.