Question

Imagine holding a basketball in both hands, throwing it straight up as high as you can, and then catching it when it falls. At which points in time does a zero net force act on the ball? Ignore air resistance.

(A) When you hold the ball still in your hands after catching it
(B) Just after the ball first leaves your hands.
(C) At the instant the ball reaches its highest point.
(D) At the instant the falling ball hits your hands.
(E) When you hold the ball still in your hands before it is thrown.

Answer 1

Answer:

(A) When you hold the ball still in your hands after catching it

(E) When you hold the ball still in your hands before it is thrown.

Explanation:

According to Newton's 1st law, objects subjected to 0 net force would maintain a constant velocity or staying at rest. This is not the case for the ball when it leaves your hands. This ball would always be subjected to gravitational acceleration g so its velocity changes. So only (A) and (E) are correct when the ball stays still in your hands.