Physics for Scientists and Engineers with Modern Physics
10th Edition
ISBN: 9781337553292
Author: Raymond A. Serway, John W. Jewett
Publisher: Cengage Learning
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Chapter 21, Problem 32AP
In 1993, the U.S. government instituted a requirement that all room air conditioners sold in the United States must have an energy efficiency ratio (EER) of 10 or higher. The EER is defined as the ratio of the cooling capacity of the air conditioner, measured in British thermal units per hour, or Btu/h, to its electrical power requirement in watts. (a) Convert the EER of 10.0 to dimensionless form, using the conversion 1 Btu = 1 055 J. (b) What is the appropriate name for this dimensionless quantity? (c) In the 1970s, it was common to find room air conditioners with EERs of 5 or lower. State how the operating costs compare for 10 000-Btu/h air conditioners with EERs of 5.00 and 10.0. Assume each air conditioner operates for 1 500 h during the summer in a city where electricity costs 17.0¢ per kWh.
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Chapter 21 Solutions
Physics for Scientists and Engineers with Modern Physics
Ch. 21.1 - The energy input to an engine is 4.00 times...Ch. 21.2 - The energy entering an electric heater by...Ch. 21.4 - Three engines operate between reservoirs separated...Ch. 21.6 - (a) Suppose you select four cards at random from a...Ch. 21.7 - An ideal gas is taken from an initial temperature...Ch. 21.7 - True or False: The entropy change in an adiabatic...Ch. 21 - A particular heat engine has a mechanical power...Ch. 21 - The work done by an engine equals one-fourth the...Ch. 21 - Suppose a heat engine is connected to two energy...Ch. 21 - During each cycle, a refrigerator ejects 625 kJ of...
Ch. 21 - A freezer has a coefficient of performance of...Ch. 21 - Prob. 6PCh. 21 - One of the most efficient heat engines ever built...Ch. 21 - Prob. 8PCh. 21 - If a 35.0% -efficient Carnot heat engine (Fig....Ch. 21 - Prob. 10PCh. 21 - Prob. 11PCh. 21 - A power plant operates at a 32.0% efficiency...Ch. 21 - You are working on a summer job at a company that...Ch. 21 - Prob. 14PCh. 21 - Prob. 15PCh. 21 - Suppose you build a two-engine device with the...Ch. 21 - A heat pump used for heating shown in Figure...Ch. 21 - Prob. 18PCh. 21 - An idealized diesel engine operates in a cycle...Ch. 21 - Prob. 20PCh. 21 - Prob. 21PCh. 21 - A Styrofoam cup holding 125 g of hot water at 100C...Ch. 21 - A 1 500-kg car is moving at 20.0 m/s. The driver...Ch. 21 - A 2.00-L container has a center partition that...Ch. 21 - Calculate the change in entropy of 250 g of water...Ch. 21 - What change in entropy occurs when a 27.9-g ice...Ch. 21 - Prob. 27PCh. 21 - Prob. 28PCh. 21 - Prob. 29PCh. 21 - Prob. 30APCh. 21 - Prob. 31APCh. 21 - In 1993, the U.S. government instituted a...Ch. 21 - In 1816, Robert Stirling, a Scottish clergyman,...Ch. 21 - Prob. 34APCh. 21 - Prob. 35APCh. 21 - Prob. 36APCh. 21 - A 1.00-mol sample of an ideal monatomic gas is...Ch. 21 - Prob. 38APCh. 21 - A heat engine operates between two reservoirs at...Ch. 21 - You are working as an assistant to a physics...Ch. 21 - Prob. 41APCh. 21 - You are working as an expert witness for an...Ch. 21 - Prob. 43APCh. 21 - Prob. 44APCh. 21 - A sample of an ideal gas expands isothermally,...Ch. 21 - Prob. 46APCh. 21 - The compression ratio of an Otto cycle as shown in...
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