The kick decreases the weight of the ball. The kick applies a contact force to the ball. The kick decreases the force of gravity acting on the ball. The kick removes friction between the ball and the ground.
I gave my students this multiple choice question: A student places a ball on the ground and kicks it. The ball moves along the ground. Why does the ball move?

Only one answer is correct among these 4 choices:
- The kick decreases the weight of the ball.
- The kick applies a contact force to the ball.
- The kick decreases the force of gravity acting on the ball.
- The kick removes friction between the ball and the ground.

Could you tell me which one is correct?

The kick applies a contact force to the ball.