Afootball punter accelerates a football from rest to a speed of 10m/sec during the time in which his toe is in contact with the ball (about 0.2 sec). if the football has a mass of 0.5 kg, what average force does the punter exert on the ball?

The average force that the punter exert on the ball is 25 N.

Explanation:

The force acting on the ball is equal to its mass times its acceleration: F=ma

You can find the acceleration using the velocity and the time given by the problem, i is for initial and f is for final:  

From the problem, you now that v_i=0 because the ball was at rest, and t_f-t_i is equal to 0.2 s.  

Now that you know the acceleration, you can replace the value in the formula for the force:  

F=25 N

The force is 25 Newtons, which is the unit to measure the force.