College Physics
1st Edition
ISBN: 9781938168000
Author: Paul Peter Urone, Roger Hinrichs
Publisher: OpenStax College
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Textbook Question
Chapter 15, Problem 18PE
Construct Your Own Problem
Consider a car's gasoline engine. Construct a problem in which you calculate the maximum efficiency this engine can have. Among the things to consider are the effective hot and cold reservoir temperatures. Compare your calculated eficiency with the actual efficiency of car engines.
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Problem 5: Suppose a Carnot engine has an efficiency of 45 % and a cold reservoir temperature of 28.5°C.
Part (a) What is the hot reservoir temperature, in degrees Celsius, of this Carnot engine?
Part (b) What must the hot reservoir temperature be, in degrees Celsius, for a real heat engine that has an efficiency of 45, which is 70% of the maximum efficiency? Assume it has the same cold reservoir, at 28.5°C.
(a) What is the hot reservoir temperature of a Carnot engine that has an efficiency of 42.0% and a cold reservoir temperature of 27.0ºC ?(b) What must the hot reservoir temperature be for a real heat engine that achieves 0.700 of the maximum efficiency, but still has an efficiency of 42.0%(and a cold reservoir at 27.0ºC )? (c) Does your answer imply practical limits to the efficiency of car gasoline engines?
Chapter 15 Solutions
College Physics
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