# Calculating frictional torque

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1. Feb 12, 2019 at 3:49 PM

### Jeviah

1. The problem statement, all variables and given/known data
Hello, so I currently designing a centrifugal brake, I know how much torque it needs to stop etc just unsure of a few things.
How would I calculate frictional torque? I understand that I can use the net torque to determine what torque is needed for equilibrium etc however I need to determine what materials I will use, required angular velocity of the axle etc and justify my choices through calculations. I am assuming that I cannot simply use the centrifugal force as the normal force and use the standard friction equation since I am dealing with torque and angular variables whereas friction in a linear value.

2. Relevant equations
N/A

3. The attempt at a solution
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2. Feb 13, 2019 at 3:06 AM

### BvU

HI,

(*) I'm afraid you will end up with differential equations very quickly; can you deal with that kind of stuff ?

3. Feb 13, 2019 at 3:21 PM

### Jeviah

I understand, I am designing a controlled descent system, although I am unsure as to how to go about my calculations. I can calculate all linear and angular values, moment of inertia as well as the torque of the system for a given set of parameters.
Then I could calculate the centrifugal force and determine the required angular velocity to create contact between the brake pads and the other surface.
At this point I am unsure of my next step as I could use the centrifugal force (essentially as the normal force) and calculate the friction force between the pad and the other surface.
I could alter the angular velocity of the centrifugal brake through gears if necessary to increase the centrifugal force but even if I know the value of the torque I am trying to counteract I do not know how I can (if I can) use that value of friction (friction coefficient x force) assuming that the value of friction calculated would be linear.

I have studied differential equations however this has been "here's the equation, what's the solution", I wouldn't know how to go about formulating an equation to describe the problem.