Question

Which statement describes the motion of a ball as it drops onto a vertical spring?

a. The acceleration of the ball decreases as the spring shrinks.
b. The accIleration of the ball decreases as the spring extends.
c. The velocity of the ball changes from positive to negative as the spring shrinks.
d. The velocity of the ball changes from negative to positive as the spring extends.

Answer 1

F = M a Newton's second law

F = - K x force exerted by compressed spring

a = - K x / M

a) is true because the ball originally is accelerated due to gravity and this acceleration will decrease as the spring in compressed

One could argue for (d) if the downward direction was designated as negative

Prior to maximum compression of the spring the velocity would negative and as the spring began to extend (and the ball began move upward) the velocity of the ball would change from negative to positive