- #1

iamtrojan3

- 56

- 0

the problem is:

A force of 15N is applied tangentially to the edge of a 0.88kg solid disc initially at rest. The radius of the disc is 0.55m. How fast will the disc be spinning after it has gone 3.0 complete rotations? (disregard all the friction/air resistance etc.)

The moment of Inertia of a solid disc is I=1/2mr^2 >> I=1/2(0.88)(0.55^2) >> I=0.1331

Torque= Lever arm x Force applied Torque= 15N x 0.55m = 8.25Nm

Torque = alpha x I >>> 8.25= alpha x 0.1331 >>> alpha = 62 (this doesnt look right )

Then just use Kenematic Equations

since 3 rotations is 6pi

W^2=Wo^2x2(alpha)(Theta)

W^2=0(62)(6pi)>>> W= 48.35radians/sec (this doesn't look right either )

Basicly my thoughts through the problem ^^^^^^^^^

Feel free to correct me on watever...i admitt, i suck/hate these problems.

Thanks