Essential University Physics: Volume 1 (3rd Edition)
3rd Edition
ISBN: 9780321993724
Author: Richard Wolfson
Publisher: PEARSON
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Textbook Question
Chapter 19, Problem 69P
Energy-efficiency specialists measure the heat Qh delivered by a heat pump and the corresponding electrical energy W needed to run the pump, and they compute the pump’s COP as the ratio Qh/W. They also measure the outdoor temperature, and they know that the pump produces hot water at Th = 52°C. The table below shows their results for Q and T. (a) Determine a quantity that, when you plot the COP against it, should give a straight line, (b) Make your plot, fit a straight line, and from it determine how the heat pump’s COP compares with the theoretical maximum COP.
| Tc(°C) | −18 | −10 | −5 | 0 | 10 |
| COP Qh/W | 2.7 | 3.2 | 3.6 | 3.7 | 4.7 |
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Chapter 19 Solutions
Essential University Physics: Volume 1 (3rd Edition)
Ch. 19.1 - Which of these processes is irreversible? (a)...Ch. 19.2 - The low temperature for a practical heat engine is...Ch. 19.3 - A clever engineer decides to increase the...Ch. 19.4 - In each of the following processes, does the...Ch. 19 - Could you cool the kitchen by leaving the...Ch. 19 - Prob. 2FTDCh. 19 - Should a car get better mileage in the summer or...Ch. 19 - Prob. 4FTDCh. 19 - Name some irreversible processes that occur in a...Ch. 19 - Your power company claims that electric heat is...
Ch. 19 - A hydroelectric power plant, using the energy of...Ch. 19 - A heat-pump manufacturer claims the device will...Ch. 19 - Prob. 9FTDCh. 19 - The heat Q added during adiabatic free expansion...Ch. 19 - Energy is conserved, so why cant we recycle it as...Ch. 19 - Why doesnt the evolution of human civilization...Ch. 19 - What are the efficiencies of reversible heat...Ch. 19 - A cosmic heat engine might operate between the...Ch. 19 - A reversible Carnot engine operating between...Ch. 19 - A Carnot engine absorbs 900 J of heat each cycle...Ch. 19 - Find the COP of a reversible refrigerator...Ch. 19 - Prob. 18ECh. 19 - The human body can be 25% efficient at converting...Ch. 19 - Calculate the entropy change associated with...Ch. 19 - You metabolize a 650-kcal burger at your 37C body...Ch. 19 - You heat 250 g of water from 10C to 95C. By how...Ch. 19 - Melting a block of lead already at its melting...Ch. 19 - How much energy becomes unavailable for work in an...Ch. 19 - Prob. 25ECh. 19 - A Carnot engine extracts 745 J from a 592-K...Ch. 19 - The maximum steam temperature in a nuclear power...Ch. 19 - Youre engineering an energy-efficient house that...Ch. 19 - A power plants electrical output is 750 MW....Ch. 19 - A power plant extracts energy from steam at 280C...Ch. 19 - The electric power output of all the thermal...Ch. 19 - Consider a Carnot engine operating between...Ch. 19 - An industrial freezer operates between 0C and 32C,...Ch. 19 - Use appropriate energy-flow diagrams to analyze...Ch. 19 - Prob. 35PCh. 19 - A refrigerator maintains an interior temperature...Ch. 19 - You operate a store thats heated by an oil furnace...Ch. 19 - Use energy-flow diagrams to show that the...Ch. 19 - A heat pump extracts energy from groundwater at...Ch. 19 - A reversible engine contains 0.350 mol of ideal...Ch. 19 - (a) Determine the efficiency for the cycle shown...Ch. 19 - A 0.20-mol sample of an ideal gas goes through the...Ch. 19 - A shallow pond contains 94 Mg of water. In winter,...Ch. 19 - Estimate the rate of entropy increase associated...Ch. 19 - The temperature of n moles of ideal gas is changed...Ch. 19 - The temperature of n moles of ideal gas is changed...Ch. 19 - A 6.36-mol sample of ideal diatomic gas is at 1.00...Ch. 19 - A 250-g sample of water at 80C is mixed with 250 g...Ch. 19 - An ideal gas undergoes a process that takes it...Ch. 19 - In an adiabatic free expansion, 6.36 mol of ideal...Ch. 19 - Find the entropy change when a 2.4-kg aluminum pan...Ch. 19 - An engine with mechanical power output 8.5 kW...Ch. 19 - Find the change in entropy as 2.00 kg of H2O at...Ch. 19 - Gasoline engines operate approximately on the Otto...Ch. 19 - The compression ratio r of an engine is the ratio...Ch. 19 - In a diesel cycle, gas at volume V1 and pressure...Ch. 19 - (a) Show that the heal flowing into the diesel...Ch. 19 - Youre considering buying a car that comes in...Ch. 19 - The 54-M W wood-fired McNeil Generating Station in...Ch. 19 - A 500-g copper block at 80C is dropped into 1.0 kg...Ch. 19 - An objects heat capacity is inversely proportional...Ch. 19 - A Carnot engine extracts heat from a block of mass...Ch. 19 - In an alternative universe, youve got the...Ch. 19 - Youre the environmental protection officer for a...Ch. 19 - Find an expression for the entropy gain when hot...Ch. 19 - Problem 74 of Chapter 16 provided an approximate...Ch. 19 - The molar specific heat at constant pressure for a...Ch. 19 - Prob. 68PCh. 19 - Energy-efficiency specialists measure the heat Qh...Ch. 19 - Refrigerators remain among the greatest consumers...Ch. 19 - The refrigerators COP is a. 13. b. 2. c. 3. d. 4.Ch. 19 - The fuel energy consumed at the power plant to run...Ch. 19 - Prob. 73PP
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