# Chapter 2 - Describing Motion: Kinematics in One Dimension - Problems: 7

a) 350 km. b) 78 km/h.

#### Work Step by Step

a. Calculate the time for the first part of the trip. $$\Delta t = \frac{180 km}{95 km/h} = 1.895 hours$$ The time for the second leg of the trip is the remainder, 2.605 hours. Find the distance for the second leg of the trip. (65 km/h)(2.605 h) = 169.3 km. The total distance is the sum of the distances for the two legs. b. The definition of average speed is the total distance over the time. $$\frac{350 km }{4.5 h} = 78 km/h$$

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