Physics for Scientists and Engineers: A Strategic Approach with Modern Physics (3rd Edition)

Published by Pearson
ISBN 10: 0321740904
ISBN 13: 978-0-32174-090-8

Chapter 19 - Heat Engines and Refrigerators - Exercises and Problems - Page 550: 18

Answer

a) $64\;\rm J$ b) $1.6$

Work Step by Step

a) We know, for refrigerator heat engines, that $$Q_H=W_{in}+Q_C$$ Hence, the heat extracted is given by $$Q_C=Q_H-W_{in}\tag 1$$ where $Q_H$ is shown in the given graph (105 J), and $$W_{in}=-W_s=-(78-119)=\bf 41\rm \;J$$ Plugging the known into (1); $$Q_C=Q_H-W_{in}=105-41$$ $$Q_C=\color{red}{\bf 64 }\;\rm J$$ ---- b) The coefficient of performance of a refrigerator is given by $$K=\dfrac{Q_C}{W_{in}}$$ Plugging the known; $$K=\dfrac{64}{41}=\color{red}{\bf 1.6}$$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.