University Physics with Modern Physics (14th Edition)

Published by Pearson
ISBN 10: 0321973615
ISBN 13: 978-0-32197-361-0

Chapter 2 - Motion Along a Straight Line - Problems - Exercises: 2.9

Answer

(a) The average velocity is 2.3 m/s. The average speed is 2.3 m/s. (b) The average velocity is 0.33 m/s. The average speed is 2.3 m/s.

Work Step by Step

(a) From t = 0 s to t = 2.0 s, the velocity is 2.0 m/s. The displacement is (2.0 m/s)(2.0 s) which is 4.0 m. The distance is also 4.0 m. From t = 2.0 s to t = 3.0 s, the velocity is 3.0 m/s. The displacement is (3.0 m/s)(1.0 s) which is 3.0 m. The distance is also 3.0 m. The total displacement is 7.0 m. The total distance is also 7.0 m. The average velocity is $\frac{7.0 ~m}{3.0 ~s} = 2.3 ~m/s$ The average speed is $\frac{7.0 ~m}{3.0 ~s} = 2.3 ~m/s$ (b) From t = 0 s to t = 2.0 s, the velocity is 2.0 m/s. The displacement is (2.0 m/s)(2.0 s) which is 4.0 m. The distance is also 4.0 m. From t = 2.0 s to t = 3.0 s, the velocity is -3.0 m/s. The displacement is (-3.0 m/s)(1.0 s) which is -3.0 m. The distance is 3.0 m. The total displacement is 4.0 m - 3.0 m = 1.0 m. The total distance is 7.0 m. The average velocity is $\frac{1.0 ~m}{3.0 ~s} = 0.33 ~m/s$ The average speed is $\frac{7.0 ~m}{3.0 ~s} = 2.3 ~m/s$
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