Flywheel shaped like a solid cylinder?

Question

with a radius of 0.499 m and mass of 10.1 kg is brought to an angular speed of 5.88 rad/s in 0.531 s by a motor exerting a constant torque. After the motor is turned off, the flywheel makes 26.8 rev before coming to rest because of friction (assumed constant during rotation).

What percentage of the power generated by the motor is used to overcome friction?

Answer 1

All of the power from the motor goes to friction because they just let the wheel coast and burn up all the energy. But, I'm sure that wasn't the intended answer for the problem

You need to make a few preliminary calculations:
First you need the Inertia of the flywheel which you can find given the mass and radius of the wheel.

Then you need to calculate the angular acceleration required to bring an object at rest up to 5.88 rad/s in 0.531 sec. Using this, you can get the torque of the motor - friction.

Finally, calculate the angular acceleration required to bring an object spinning at 5.88 rad/s down to rest in 26.8 revolutions. Using this, you can get the torque of the friction by itself.

Add the second result from the first to get the torque of the motor. Take the friction torque and divide by the motor torque times 100 to get percentage of friction.

Answer 2

at start up, some...after that a balance exists between friction or drag and enerisha