The runners in the picture below have just started a race. They started at rest and are getting faster.

Question

What statement best describes the motion of the runners at the beginning of the race?
A.
Acceleration and speed both remain constant.
B.
Velocity and speed both remain constant.
C.
Velocity remains the same and speed is positive.
D.
Acceleration is positive and speed is increasing.

Answer 1

The statement that best describes the motion of the runners at the beginning of the race is:

D. Acceleration is positive and speed is increasing.

Since the runners are starting from rest and getting faster, this indicates that they are accelerating, and their speed is increasing from zero.