Fundamentals of Physics Extended (10th Edition)

Published by Wiley
ISBN 10: 1-11823-072-8
ISBN 13: 978-1-11823-072-5

Chapter 2 - Motion Along a Straight Line - Problems - Page 34: 25a

Answer

30 seconds

Work Step by Step

The vehicle has an initial velocity of v0 = 0 m/s (it is at rest). It initially accelerates at $2.0m/s^2$ until it reaches a speed of 20m/s. We use the equation $ v = v0 +at $ to find the time it took for it to reach the 20m/s $20 = 0 + (2m/s^2)t $ so then t = 10 s It then slows at a constant rate of $ 1.0m/s^2$, a = -1 $m/s^2$ (since it is slowing down) and once again we solve the equation. Here, v0 = 20m/s and v = 0 (since it stops) $ 0 = 20 + (-1.0m/s^2)t $ so then t = 20 seconds Adding the two together we get that t = 10 + 20 = 30 seconds
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