A runner circles a track of radius 100 m one time in 100 s at a constant rate.The greatest change in his velocity from his starting velocity:
A) occurs one-fourth of the way around the track.
B) occurs one-half of the way around the track.
C) occurs three-fourths of the way around the track.
D) Both a and c are correct.

Question

Quizplus · Accepted Answer

Since the runner is moving at a constant rate, his velocity is always tangential to the circle. Therefore, the only way his velocity can change is if his direction changes. The greatest change in direction occurs at the point farthest from the starting point, which is halfway around the track. Thus, the greatest change in velocity occurs at this point as well. Therefore, the correct answer is B.

A Runner Circles a Track of Radius 100 M One