Physics (High School)
posted by Ama on .
A 7.24 g bullet moving at 636 m/s penetrates a tree to a depth of 4.87 cm. Use energy considerations to find the average frictional force that stops the bullet. Answer in units of N
B) Assuming that the frictional force is constant how much time elapsed between the moment of the bullet entering the tree and moment it stopped? Answer is Seconds

A) Initial Kinetic Energy
= Work done to stop
= (Avg. Force)*(Distance, X)
F = (1/2)(0.00724)*(636)^2/0.0487 m)
= ___ N
B) (Avg speed)*time = Distance
Time = 0.0487 m/318 m/s
= 1.53*10^4 s