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 175: 14


a). $147.5kJ$ b). $-122.5kJ$ c). $25kJ$

Work Step by Step

a). $h=\frac{1}{2}at^{2}=25m$ $F=m(g+a)=500(9.8+2)=5900N$ $W=5900\times25=147.5kJ$ b). $W=mgh=500\times(-9.8)\times25=-122.5kJ$ c). Net work done on helicopter $W=147.5-122.5=25kJ$
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