posted by Andrea .
There is a door that is 1.0 m wide and can rotate about a vertical axis without friction. The door’s mass is 15 kg and is free to swing open. Someone fires a 10 g bullet at 400 m/s into the exact center of the door, perpendicular to it.
Find the angular velocity of the door just after the bullet sticks in the door.
Show whether kinetic energy is conserved.