A bullet with a mas of 10 g and an initial velocity of 800m/s penetrates 5 cm into a fixed block of wood before stopping. The average force on the buller by the wood is? A block of mass 4.25 kg hanging from a light string is struck by a projectile of mass 250 g. The projectile sticks to the mass after collision and the two together rises a vertical distance of 12 cm. What is the velocity of the two-mass system immediately after collision? A 5-kg object moving with a velocity of 4m/s colides head on with a 10-kg object moving towards it at -3m/s. If teh 10-kg object stops dead after the collision, what is the approximate coefficient of restitution for this collision?