1. The problem statement, all variables and given/known data I have a gyrocompass with a fixed axis at an angle alfa to the rotational axis of the earth. Omega "Erde" is the angular momentum vector of the earth and Omega K is accordingly of the gyrocompass. The whole mass of the gyrocompass (m=0.1kg) is concentrated on the edge at a distance of R=1cm from the center of mass. The Gyrocompass is rotating with 10 000 RPM. I have to calculate the torque induced in the gyrocompass by the angle to the earth rotational axis. 2. Relevant equations I guess that because of the form of the gyrocompass its moment of inertia should be I = m*r^2 Angular momentum = I*omega Torque = I*omega' Omega K = 2*pi / T T (Period) = 60/10000 3. The attempt at a solution I tried calculating the Omega Z component of the angular momentum of the gyrocompass with Cos(alfa)*Omega K, which I find via the moment of inertia and RPMs. Then I calculated the torque using only the Omega Z component, but that shouldn`t be correct, because the effect of the Earth angular moment isn`t taken into account and conservation of angular momentum, too. Any ideas would be greatly appreciated! By the way this is pretty urgent, I have to have it ready by tomorrow!