Essential University Physics: Volume 1 (3rd Edition)

Published by Pearson
ISBN 10: 0321993721
ISBN 13: 978-0-32199-372-4

Chapter 6 - Section 6.4 - Kinetic Energy - Example - Page 100: 6.6

Answer

a) $ 220 kJ$ b) $ -490 kJ$

Work Step by Step

We know that work is equal to change in kinetic energy. Recall, it is necessary to convert kilometers per hour into meters per second in order to do this problem. Thus: $W = \frac{1}{2}m(v_f^2 - v_0^2)$ a) $W = \frac{1}{2}(1400)(26.4^2 - 19.4^2) = 220 kJ$ b) $W = \frac{1}{2}(1400)(0^2 - 26.4^2) = -490 kJ$
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