Solve the all parts of given question:
Question: A 7.80-g bullet moving at 600 m/s penetrates a tree trunk to a depth of 5.60 cm.
Part A: Use work and energy considerations to find the average frictional force that stops the bullet.
Part B: Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.
I want help to find the average frictional force that stops the bullet.