Question

A ball is thrown upward and allow to fall under the influence of gravity. We will ignore the effects of air resistance. We consider three times: Time A, when the ball is first thrown upward, Time B when the ball reaches the peak, and Time C when the ball hits the ground. Rank the power delivered by the gravitational force to the ball at those three times from least to greatest.

a. A=C<B
b. A=C=B
c. B<A=C
d. C<B<A
e. A<B<C

I believe that since the ball has ended up in the same spot, the same amount of power was exerted at points A and C but not at point B. My answer to this problem is C...
Is this thinking correct?

Answer 1

Yes

Answer 2

The answer is (e). The power delvered at A is negative as displacement and force mg are oposite.Power delivered at B is zero and at C it is positive as mg and displacement are in the same direction.
A<B<C