COLLEGE PHYSICS
2nd Edition
ISBN: 9781464196393
Author: Freedman
Publisher: MAC HIGHER
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Chapter 15, Problem 32QAP
To determine
(a)
Estimate the work (in J) done in driving a car across America
To determine
(b)
If the energy required to do that work were added to an Olympic sized swimming pool, how much would the temperature of water rises?
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A 4-ton air conditioner removes 5.06×107 J (48,000 British thermal units) from a cold environment in 1.00 h. (a) What energy input in joules is necessary to do this if the air conditioner has an energy efficiency rating ( EER ) of 12.0?
(b) What is the cost of doing this if the work costs 10.0 cents per 3.60×106J (one kilowatt-hour)? (c) Discuss whether this cost seems realistic. Note that the energy efficiency rating ( EER ) of an air conditioner or refrigerator is defined to be the number of British thermal units of heat transfer from a cold environment per hour divided by the watts of power input.
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A 60-kg hiker wishes to climb to the summit of Mt. Ogden, an ascent of 5000 vertical feet (1500 m).
a.) Assuming that she is 25% efficient at converting chemical energy from food into mechanical work, and that essentially all the mechanical work is used to climb vertically, roughly how many bowls of corn flakes (standard serving size 1 ounce, 100 kilocalories) should the hiker eat before setting out?(b) As the hiker climbs the mountain, three-quarters of the energy from the corn flakes is converted to thermal energy. Ifthere were no way to dissipate this energy, by how many degrees would her body temperature increase?(c) In fact, the extra energy does not warm the hiker's body significantly; instead, it goes (mostly) into evaporating water from her skin. How many liters of water should she drink during the hike to replace the lost fluids? (At 25°C, a reasonable temperature to assume, the latent heat of vaporization of water is 580 cal/g, 8% more than at 100°C.)
Chapter 15 Solutions
COLLEGE PHYSICS
Ch. 15 - Prob. 1QAPCh. 15 - Prob. 2QAPCh. 15 - Prob. 3QAPCh. 15 - Prob. 4QAPCh. 15 - Prob. 5QAPCh. 15 - Prob. 6QAPCh. 15 - Prob. 7QAPCh. 15 - Prob. 8QAPCh. 15 - Prob. 9QAPCh. 15 - Prob. 10QAP
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