A 7.80 g bullet is initially moving at 500 m/s just before it penetrates a block of solid rubber to a depth of 4.50 cm. (a)What is the magnitude of the average frictional force (in N) that is exerted on the bullet while it is moving through the block of solid rubber? Use work and energy considerations to obtain your answer.
(b)Assuming the frictional force is constant, how much time (in s) elapses between the moment the bullet enters the block of solid rubber and the moment it stops moving?