A bullet of mass 0.04 kg moving with a speed of 90 m s^(-1)enters a heavy wooden block and is stopped after a distance of 60 cm. What is the average resistive force exerted by the block onthe bullet?

A bullet of mass 0.04 kg moving with a speed of 90 m s^(-1)enters a he

1.	A bullet of mass 0.04 kg moving with a speed of 90 m s^(-1)enters a heavy wooden block and is stopped after a distance of 60 cm. What is the average resistive force exerted by the block onthe bullet?
Answer» Solution :The RETARDATION ‘a’ of the bullet (assumed constant) is GIVEN by `a= ( -u^2)/(2s)= (-90 xx 90)/(2 xx 0.6) ms^(-2) = - 6750 ms^(-2)` The retarding force, by the second law of motion, is `= 0.04 kg xx 6750 m s^(-2) = 270 N ` The actual resistive force, and THEREFORE, retardation of the bullet may not be uniform.The answer therefore, only indicates the average resistive force.