A4.2

Principles of Dynamics
Part II, 2002

Explain how the orientation of a rigid body can be specified by means of the three Eulerian angles, θ,ϕ\theta, \phi and ψ\psi.

An axisymmetric top of mass MM has principal moments of inertia A,AA, A and CC, and is spinning with angular speed nn about its axis of symmetry. Its centre of mass lies a distance hh from the fixed point of support. Initially the axis of symmetry points vertically upwards. It then suffers a small disturbance. For what values of the spin is the initial configuration stable?

If the spin is such that the initial configuration is unstable, what is the lowest angle reached by the symmetry axis in the nutation of the top? Find the maximum and minimum values of the precessional angular velocity ϕ˙\dot{\phi}.