# Constant Torque Find magnitude of friction force

1. Oct 24, 2009

### sarahjt1

1. The problem statement, all variables and given/known data
A grinding wheel of radius 0.330m rotating on a frictionless axle is brought to rest by applying a constant friction force tangential to its rim. The constant torque produced by this force is 72.1 N*m. Find the magnitude of the friction force.

I'm honestly lost at even starting this problem but below are some equations that I THINK are relevant but I don't really know.

2. Relevant equations

torque=I alpha, where I = 1/2MR^2.

This is where I get confused because we are not given a mass.............

3. The attempt at a solution

2. Oct 24, 2009

### sarahjt1

Nevermind... silly me. Much simpler than I thought.