The figure shows vectors representing the angular velocity of precession $\omega$_p and the spin velocity $\omega$_s.The associated torque vector points along which of the axes? A)-x B)y C)z D)-z E)None of these is correct.

Question

Quizplus · Accepted Answer

The torque vector is given by the cross product of the angular momentum and the angular velocity. Since the angular momentum is pointing in the y-direction (perpendicular to the plane of rotation), taking the cross product with the precession velocity vector (pointing along the z-axis) gives a torque vector along the x-axis. Taking the cross product with the spin velocity vector (pointing along the y-axis) gives a torque vector along the z-axis. However, since the precession velocity is much larger than the spin velocity, it dominates the torque vector and we get a torque vector along the x-axis.

The Figure Shows Vectors Representing the Angular Velocity of Precession ω\omegaω

The Figure Shows Vectors Representing the Angular Velocity of Precession $\omega$