All Problems

Dynamics of a solid body

Problem 1.283

A top of mass \(m=0.50 \mathrm{~kg}\), whose axis is tilted by an angle \(\theta=30^{\circ}\) to the vertical, precesses due to gravity. The moment of inertia of the top relative to its symmetry axis is equal to \(I\) \(=2.0 \mathrm{~g} \cdot \mathrm{m}^{2}\), the angular velocity of rotation about that axis is equal to \(\omega=350 \mathrm{rad} / \mathrm{s},\) the distance from 'the point of rest to the centre of inertia of the top is \(l=10 \mathrm{~cm} .\) Find: (a) the angular velocity of the top's precession; (b) the magnitude and direction of the horizontal component of the reaction force acting on the top at the point of rest.

Reveal Answer
1.283. (a) \(\omega^{\prime}=m g l / I \omega=0.7 \mathrm{rad} / \mathrm{s}\) (b) \(F=m \omega^{\prime 2} l \sin \theta=10 \mathrm{mN}\). See Fig. 11.