# Gyroscopic forces on flywheel

1. Jul 27, 2011

### doodaa

Hi there,

I need to calculate bending torques on a rotating flywheel. Not sure how to do this. Anyone who can help?

I have a disc with radius r and mass m rotating with omega_z. This means that the moment of inertia is m*r^2/4 for x and y axis and m*r^2/2 for z axis. (Z-axis is the "natural" center axis of the disc).

If I rotate the spinning disc around the x-axis (or y-axis) I will feel a torque in the y-axis (or x-axis) due to gyroscopic effects. But how does it relate?

2. Jul 28, 2011

### Staff: Mentor

I'm not very familiar with flywheels. What do you mean by "bending torque"?

3. Jul 29, 2011

### doodaa

Well, flywheel or not. Let's just assume it is a rotating disc. Bending torque is ortoghonal to the rotating torque. For exampel, if you have a front wheel driven car the rotating torque accelerates the car and the bending torque turns the wheel.

4. Jul 30, 2011

### Cleonis

A discussion of that relation is presented by professor Walter Lewin in lecture 24 of his classical mechanics series, available as a youtube video: