question_answer 24)

A bullet of mass 10 g and speed 500 m/s is fired into a door and gets embedded exactly at the centre of the door. The door is 1.0m wide and weighs 12 kg. It is hinged at one end and rotates about a vertical axis practically without friction, find the angular speed of the door just after the bullet embeds into it. (Hint. The moment of inertia of the door about the vertical axis at one end is )  

Answer:

By the principle of conservation of angular momentum, Initial angular momentum of the bullet = Final angular momentum of the door or            or             or   Here,