Suppose there is a rotating wheel at constant angular speed, i.e, 1000 RPM (Revolution Per Minute). What is the torque of Earth at certain location? The equator should have the maximum torque value. I find the angular speed w by 1000 x 2Pi rad x 1 / 60s = 104.71 rad/s Assume M is the mass of the rotating wheel. R is the radius. Because it's revolving at a constant angular speed, the tangential angular acceleration (alpha t ) is zero. I can get the inertia (I) and kinetic energy K by formulas. Then, I'm kind of stuck how to find out the torque? Read through the rotation chapter of physics book have twice, checked all the examples without success. What am I missing here? Thanks in advance.