# Torque On Disk

1. Mar 12, 2012

### ctwokay

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

A uniform disk with mass m = 9.32 kg and radius R = 1.37 m lies in the x-y plane and centered at the origin. Three forces act in the +y-direction on the disk: 1) a force 340 N at the edge of the disk on the +x-axis, 2) a force 340 N at the edge of the disk on the –y-axis, and 3) a force 340 N acts at the edge of the disk at an angle θ = 30° above the –x-axis.

Q: If the disk starts from rest, what is the rotational energy of the disk after the forces have been applied for t = 1.5 s?

2. Relevant equations

I=1/2*mR^2
τ=I*alpha
ω=ωi+alpha*t
E=1/2*I*ω^2

3. The attempt at a solution
I just want to check whether my working is correct or not.

I use ω=ωi+alpha*t which ωi is zero,then i sub in the values to E=1/2*I*ω^2 to find the rotational energy.
Thank you.

2. Mar 12, 2012

### tiny-tim

hi ctwokay!

(have an alpha: α and try using the X2 and X2 buttons just above the Reply box )
yes, that's fine!

3. Mar 12, 2012

### ctwokay

thank you very much