To catch a ball, a baseball player extends her hand forward before Impact with the ball and then lets it ride backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because the

a. relative velocity is less
b. force of impact is reduced
c. time of impact is decreased
d. time of impact is increased

Option A

Explanation:

When she moves her hand in the same direction that the ball, the speed in which the hand "sees" the ball (or a viewer in the frame of the motion of the hand) is smaller.

This means that the difference in the kinetic energy (that is written as k = (1/2)m*v^2) between the and the ball is smaller, then the change in the kinetic energy of the hand when the ball impacts it is also smaller, then the "force" of the impact is smaller.

The correct answer would be A, the relative velocity of the ball is less, which translates into a reduction in the force of impact (or the change in the kinetic energy of the hand)

b. a lightning bug, plug of grass, and a worm