College Physics (7th Edition)

Published by Pearson
ISBN 10: 0-32160-183-1
ISBN 13: 978-0-32160-183-4

Chapter 5 - Work and Energy - Learning Path Questions and Exercises - Exercises - Page 176: 30


a). $375kJ$ b). $375kJ$

Work Step by Step

a). m=1200kg, v=$90km/hr=90\times\frac{1000m}{3600s}=25m/s$ KE=$\frac{1}{2}\times1200\times25^{2}=375kJ$ b). To stop the car, the work to be done should be equal to the initial KE because the velocity becomes zero finally as is the KE. So, work to be done is $375kJ$.
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