# Homework Help: Cylinder Question

1. Oct 25, 2007

### sheri1987

1. The problem statement, all variables and given/known data

M, a solid cylinder (M=1.67 kg, R=0.137 m) pivots on a thin, fixed, frictionless bearing. A string wrapped around the cylinder pulls downward with a force F which equals the weight of a 0.670 kg mass, i.e., F = 6.573 N. Calculate the angular acceleration of the cylinder.

2. Relevant equations

F*R ?
ang accel. = alpha*R

3. The attempt at a solution

I multiplied Force*Radius, cause someone told me to start with that, but I'm not sure what to do next? Do I have to use a=9.81 m/s^2? I'm not really good at this stuff so if someone could help me that would be great!! thanks!

2. Oct 25, 2007

### Dick

You already did use a=9.81m/s^2 when you found the weight of the hanging mass.

3. Oct 25, 2007

### sheri1987

so should I still do Force * radius...then what?

4. Oct 25, 2007

### Dick

Force*radius is torque. Then you need to find moment of inertia. Then T=I*omega. Just like F=ma, right?

5. Oct 25, 2007

### dynamicsolo

I think you want I ยท alpha there , since alpha is angular acceleration.

6. Oct 25, 2007

### Dick

Oh, yeah. I had a funny feeling while I was writing it. Guess I'm forgetting what greek letters look like written in english. Thanks.