College Physics (7th Edition)

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

Chapter 2 - Kinematics: Description of Motion - Learning Path Questions and Exercises - Exercises - Page 60: 7


(a) Average speed is $74.73\,\mathrm{km/h}$. (b) Average velocity is zero.

Work Step by Step

(a) Total distance traveled, $d=300+300=600\,\mathrm{km}$ Total time taken, $t=\frac{300}{75}+0.5+\frac{300}{85}=8.03\,\mathrm{h}$ Average speed, \begin{align*} s&=\frac{d}{t}=\frac{600}{8.03}\\&=74.73\,\mathrm{km/h} \end{align*}(b) Since net displacement is zero, average velocity is zero.
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