# Homework Help: Block and pulley

1. Mar 22, 2006

### highlander2k5

I'm trying to solve this problem and I can get one part but not the other. Here is the information I was given: A uniform, cylindrical pulley of mass M=3.30 kg and radius R=0.660 m rotates freely about a fixed horizontal axis. A block which moves downward is attached to a string of tension T=3.40 N which is wrapped around the pulley.

The first part asks me to find angular acceleration of the pulley which I was able to do with this equation I rearranged Ay = 2T/MR. When plugging in the numbers I got 3.12 rad/s^2.

The second part asks me to find the mass of the block which I have not been able to figure out. I've tried using these equations T = .5MAy and
mg - .5MAy = mAy (rearranging them to find M). I was wondering if someone could guide me in the right direction to solve for the mass. Thanks.

2. Mar 23, 2006

### stunner5000pt

i could be wrong on this, but ill give it a crack anyway

can you find the linear acceleration of the cylindrical block? THis linear acceleration is the related to the tension this way

ma = mg - T
i think you can find the mass now

isnt the tension given to you at 3.40N??

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