Imagine you have an electric motor sitting upright (so spindle pointing towards the sky) with a metal disc attached to the spindle. Now imagine that you have some metal rod that is being pressed down on the disc exerting a frictional force at a distance from the center of r/2 (where r is radius).

I know the equation that power= torque*angular velocity... but im unsure what to include as torque.

Obviously the frictional force(F_f) exerts a "stopping" torque of F_f * r/2 but would you also need to calculate the torque to get the disc spinning on its own, E.g Torque= I*angular acceleration?

If so, how do you calculate angular acceleration?

Also, if you came up with a resistive torque of X, then would the torque of the motor need to be X+1 or whatever to get the thing to actually spin up?

Many thanks, Kalus