21–70. The 1-lb top has a center of gravity at point G. If it spins about its axis of symmetry and precesses about the vertical axis at constant rates of vs = 60 rad>s and vp = 10 rad>s, respectively, determine the steady state angle u. The radius of gyration of the top about the z axis is kz = 1 in., and about the x and y axes it is kx = ky = 4 in.
*21–72. The 0.25 kg football is spinning at vz = 15 rad>s as shown. If u = 40°, determine the precession about the z axis. The radius of gyration about the spin axis is kz = 0.042 m, and about a transverse axis is ky = 0.13 m.
Z
u
vp = 10 rad/s
z
z
Gvs = 60 rad/s
G
Prob. 21–72
3 in.
x
O
y