UPDATE: I have clarified my question for answerers to better understand what I am asking

If I have a flywheel, like the one shown in this image, and I know the torque, weight distribution, and weight. How do I know the drag of the flywheel, and resulting speed of this flywheel in full motion?

Just a heads up, I don't really know anything about physics.

enter image description here

  • $\begingroup$ what are your google search terms? ... it os unclear how weight factors into your question $\endgroup$
    – jsotola
    Commented Nov 25, 2020 at 2:10
  • $\begingroup$ if you must have weight in the equation, then you have left out other necessary parameter $\endgroup$
    – jsotola
    Commented Nov 25, 2020 at 19:34

1 Answer 1


Torque is moment of inertia times angular acceleration. Theoretically, if you could provide a constant torque and there were no losses, you could accelerate to an infinite speed even with a small torque.

In reality, though, losses exist. Frictional losses are based solely on load weight, like static and dynamic friction in a bearing. There's also viscous damping, which is proportional to speed.

Given "enough time," your speed will equalize because the damping losses will exactly equal the applied torque. If you know how much torque you're applying and what the steady state speed is, then you can calculate the losses.

If you know what the damping constant is then you can calculate the ultimate speed for a given torque.

If you don't have either then there's nothing really you can do, though. You can try to get numbers from other systems but little differences in fiction could make the difference between 10,000 and 30,000 rpm, for example.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.