Chapter 4, Problem 11RQ

When can the net force on a ball be zero when you kick it?

To determine

The condition, when net force on a ball is zero after it is kicked.

Answer to Problem 11RQ

The condition, when net force on a ball is zero after it is kicked is when the ball is kicked by two players at the same time from the opposite direction with the same magnitude.

Explanation of Solution

When a player kicks a ball, then the interaction of forces between the ball and player's foot takes place due to which both exert the same force on each other, that is, action and reaction. The reaction force exerted on the ball have to be balanced from the opposite end to cancel the effect of the first reaction force.

Hence, the net force on the ball becomes zero only, when two players kick it from the opposite side at the same time with the same magnitude. At this condition, the reactions of the ball are balanced by each other and cause the net force on the ball is zero.

Conclusion:

Therefore, the condition, when net force on a ball is zero after it is kicked is when the ball is kicked by two players at the same time from the opposite direction with the same magnitude.