# Rotational motion problem

1. Mar 29, 2006

### N_L_

I figured out the first part of the problem below, but I haven't been able to solve the second part.

What I have so far:

I solved for angular acceleration with alpha = v / r1 * t. I got 92.2 rad / s^2.

But, I'm not sure how to go about finding the force required of the triceps...any ideas?

2. Mar 29, 2006

### moose

I think it wants you to look at it as if it were a lever, 2.5cm on one side, 31cm on the other side. If you calculate the mechanical advantage, you will be able to get the force, I believe.

EDIT: Is that in the Giancoli Physics text? If so, what page is that on?

3. Mar 30, 2006

### N_L_

Thank you. Unfortunately we have not discussed levers yet and are just in the middle stages of torque. Mechanical advantage is in the next chapter, I think.

Yes, it is Giancoli (Sixth) page 221.

4. Mar 30, 2006

### andrevdh

The triceps muscle applies a torque $\tau$ to the forearm. How is this related to the angular acceleration, $\alpha$, of the forearm and ball?