A 8.0g bullet travelling at 400m/s passes through a heavy block of wood in 4.0x10^-4s, emerging with a velocity of 100m/s. Ignore the motion of the wood. 1) What is the force exerted by the block on the bullet? 2) What is the force exerted by tbe bullet on the block? 3) How thick is the bullet? I've gotten 1 and 2 but I have no idea how to solve the 3rd one. Can someone please help me out?