### Angular momentum and velocity question, help

Posted:

**Fri Apr 25, 2008 7:36 am**Hi, this is a question i came across and have been struggling with, some help would be great!

The 15kg plate shown is able to rotate on its axle which is supported on the journal

bearings at A and B. A bullet is fired into the plate providing it with an initial

angular momentum of 9kgm/s. Find the angular velocity of the plate when it has

rotated through 180 degrees from the position shown. (Neglect the mass of the bullet

compared with that of the plate).

The main problem i have is im not sure how to get the moment of inertia, im pretty sure i have to work it out about the y axis shown. im not sure if i have to take into account position vectors and such either. anyway any help on where to get started and what equations i need to use would be great.

Thanks

The 15kg plate shown is able to rotate on its axle which is supported on the journal

bearings at A and B. A bullet is fired into the plate providing it with an initial

angular momentum of 9kgm/s. Find the angular velocity of the plate when it has

rotated through 180 degrees from the position shown. (Neglect the mass of the bullet

compared with that of the plate).

The main problem i have is im not sure how to get the moment of inertia, im pretty sure i have to work it out about the y axis shown. im not sure if i have to take into account position vectors and such either. anyway any help on where to get started and what equations i need to use would be great.

Thanks