# Homework Help: Finding Coefficient of friction with limited info

1. Apr 3, 2013

### shcksdid

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

A wheel has a radius of 0.4m . The engine exerts a torque on the wheel of 290 Nm. FInd the coefficient of friction.

2. Relevant equations

T=RFsin
T= Angular acceleration * Inertia (1/2MR^2)?

3. The attempt at a solution
My friend asked me this question, but I feel like there should be more information. Just based on these info, how can you solve this question? Do I set the two equation equal and find for F? What would be the angular acceleration?

2. Apr 4, 2013

### Staff: Mentor

Welcome to the PF.

Is there a diagram that goes with this question? We need some way to relate the frictional force to the retardation of the wheel. Is all of the frictional force applied at the outer edge of the wheel?

3. Apr 4, 2013

### shcksdid

Thanks for the reply. I'm sorry but these were the only values that were given to me. So, is it impossible to solve this question from just the given information?

4. Apr 4, 2013

### Staff: Mentor

The problem does seem under-defined to me. You can assume that the frictional force is exerted at the outside edge of the disk, but what normal force is involved? Can you try to get more info?