Conical pendulum with shortening string A particle is suspended from a support by a light inextensible string which passes through a small fixed ring vertically below the support.
Initially the particle is performing a conical motion of angle 60°, with the moving part of the string of a. The support is now made to move slowly upwards so that the motion remains nearly conical.
Find the angle of this conical motion when the support has been raised by a distance a/2.
[Requires the numerical solution of a trigonometric equation.]