Frictional Force Homework: Calculating Time to Stop

[borobeauty66]

Homework Statement

A rotating disk of radius 2.0m (the mass on the disk, assume is negliable) with 4 points of mass each spaced 90 degrees apart from each other, each weighing 19kg. Each is position 0.2m from the axle.
Inertia of the disk is 3.04 kg m^2
Angular Speed is 310 rad/s
Torque is initially at 0 Nm, as no force is acting upon it.

A frictional force is then applied to the rim, of 94 N. How long does it take to come to a complete stop?

Homework Equations

I assume F x r = torque
But after this, I'm not sure where to go.

The Attempt at a Solution

Not sure where to begin

 

[BruceW]

You've got the right idea in your 'relevant equations' section. You can calculate the torque using the information given. That's the first step you should try.

 

[borobeauty66]

You've got the right idea in your 'relevant equations' section. You can calculate the torque using the information given. That's the first step you should try.

Therefor torque = 94 N x 2.0 m = 188 N m.

Will I need inertia for the next step?

 

[LawrenceC]

"Will I need inertia for the next step?"

It's a rotating object that is being stopped. What does that tell you?

 

[BruceW]

Therefor torque = 94 N x 2.0 m = 188 N m.

Will I need inertia for the next step?

This is correct.