Question

A soccer player is running at a constant velocity toward the north end. On the soccer field he quickly stops turns 180 degrees and runs twice as fast in the opposite direction. Which of the following best represents his velocity? a) Velocity decreases to zero

b) Velocity remains constant
c) Velocity doubles
d) Velocity becomes negative and doubles

Answer 1

The player's velocity becomes negative relative to the initial direction of motion and doubles in magnitude after he turns around and runs in the opposite direction.

Step-by-step explanation:

The soccer player's velocity changes when he stops and turns around to run in the opposite direction at twice the speed. Since velocity is a vector quantity with both magnitude (speed) and direction, a change in either affects velocity. When the player stops, the velocity decreases to zero, and when he turns 180 degrees and runs at twice the previous speed, the direction of the velocity changes (to the opposite direction) and the magnitude doubles. Hence, the best description of what happens to the player's velocity is that the velocity becomes negative (assuming north is positive) and doubles.