Average force?

Question

During an autumn storm, a 0.012 kg hail stone traveling at 20 m/s made a .20 cm deep dent in the hood of a person's car. What average force did the car exert to stop the damaging hail stone?

Answer 1

Kinetic energy of the hail stone equal to the work done by the average force exerted by car:
Ke=Fs

F=Ke/s

F= (1/2)mV^2/s

F= 0.5 x 0.012 x (20)^2 /.0020
F=1200N