Someone fires a 0.04 kg bullet at a block of wood that has a mass of 0.5 kg. the block of wood is sitting on a frictionless surface, so it moves freely when the bullet hits it. the wood block is initially at rest. the bullet is travelling 300 m/s when it hits the wood block and sticks inside it. now the bullet and the wood block move together as one object. how fast are they traveling?