question_answer

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 1.0 m wide and weighs 12 Kg. It is hinged at one end and rotates about a vertical axis practically without friction. The angular speed of the door just ager the bullet embeds into it will be:                           [JEE ONLINE 09-04-2013]

A)         6.25 rad/sec    

B)        0.625 rad/sec

C)   3.35 rad/sec    

D)        0.335 rad/sec

Correct Answer: B

Solution :

[b] From conservation of angular momentum             (from parallel axes theorem)