5.18 Consider an anelastic medium cycled at frequency \omega.

Show that there is a phase difference between stress and strain, amounting to
1/(*Q* \omega) seconds. [You may assume *Q* >> 1, and the discussions in Box 5.5 and
following equation (5.82).]

Does the stress lead the strain, or the strain lead the stress?

On a plot of strain against stress, there will be a hysteresis loop. Evaluate
its area, and show that this is consistent with the first definition of *Q* given in Box 5.7 [whoops: in the April 2009
paperback it said Box 5.5 here, which is wrongâ€¦].