1. A 70kg man running at 1m/s jumps on a stationary 1kg skateboard and continues rolling in the direction he was running. Calculate his velocity as he rolls neglecting friction forces.
2. A 10g bullet hits the 1kg target and gets stuck in it. Calculate the bullet's initial velocity if the target started moving at 9.9m/s right after the collision.
3. A car traveling at 45mph hits another car of the same mass stopped at the intersection. Calculate their mass if they move at 22.5 mph after absolutely inelastic collision.