Question: Four equally massive particles can be made to rotate, equally spaced, around a circle of radius r. This is physically possible provided the radius and period T of the rotation are chosen so that the following action function is at its global minimum:
A(r) = (r2/T) + (T/r), r > 0
(a) Find the radius r at which A(r) has a global minimum.
(b) If the period of the rotation is doubled, determine whether the radius of the rotation increases or decreases, and by approximately what percentage.