Fundamentals of Physics Extended (10th Edition)

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

Chapter 4 - Motion in Two and Three Dimensions - Problems - Page 89: 85a

Answer

The distance from the starting point is $~~2.7~km$

Work Step by Step

We can assume that the initial direction is north. We can find the distance and direction of each section of the trip: $x_1 = (50~km/h)(\frac{2.0~min}{60~min}) = \frac{5}{3}~km~(north)$ $x_2 = (20~km/h)(\frac{4.0~min}{60~min}) = \frac{4}{3}~km~(east)$ $x_3 = (20~km/h)(\frac{1.0~min}{60~min}) = \frac{1}{3}~km~(south)$ $x_4 = (50~km/h)(\frac{1.0~min}{60~min}) = \frac{5}{6}~km~(east)$ $x_5 = (20~km/h)(\frac{2.0~min}{60~min}) = \frac{2}{3}~km~(south)$ $x_6 = (50~km/h)(\frac{0.5~min}{60~min}) = \frac{5}{12}~km~(east)$ We can find the east component $x_2+x_4+x_6 = \frac{4}{3}~km+\frac{5}{6}~km+\frac{5}{12}~km = \frac{31}{12}~km$ We can find the north component $x_1+x_3+x_5 = \frac{5}{3}~km-\frac{1}{3}~km-\frac{2}{3}~km = \frac{2}{3}~km$ We can find the distance from the starting point: $d = \sqrt{(\frac{31}{12}~km)^2+(\frac{2}{3}~km)^2} = 2.7~km$ The distance from the starting point is $~~2.7~km$
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