Question

A dog runs 120 m away from its master in a straight line in 9.0 s, and then runs halfway back in one-third the time. Calculate (a) its average speed and (b) its average velocity :

Answer 1

The average speed of the dog is 15 m/s while the average velocity is 5 m/s.

Step-by-step explanation:

For part (a), the average speed, we need to consider the total distance traveled by the dog and the total time taken. The dog travels 120 m away from its master and then half-way back, so the total distance is 120 m + (0.5 * 120 m) = 180 m. The total time taken is 9.0 s (for the run away) + (9.0 s / 3) (for the run back) = 12.0 s. So, the average speed equals the total distance divided by the total time, which gives 180 m / 12.0 s = 15 m/s .

For part (b), the average velocity, we need to know the total displacement (change in position) and the total time. Because the dog runs back toward its master, its final position is not the same as the total distance. It ends up only 60 m away from the master (120 m - 60 m). With the total time of 12.0 s, the average velocity equals the displacement divided by the time, giving 60 m / 12.0 s = 5 m/s .

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