Calc Angular Accel of Solid Cylinder - FxR Method

[sheri1987]

1. Homework Statement


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. Homework 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!

 

[Dick]

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

 

[sheri1987]

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

 

[Dick]

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

 

[dynamicsolo]

Then T=I*omega. Just like F=ma, right?

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

 

[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.