A light thread is tightly wrapped around a fixed disc of radius R. A particle of mass m is tied to the end P of the thread and the vertically hanging part of the string has length `piR`. The particle is imparted a horizontal velocity `V=sqrt((4pigR)/3)`. The string wraps around the disc as the particle moves up. At the instant the velocity of the particle makes an angle of `theta=60^(@)` with horizontal, calculate.

(a) Speed of the particle
(b) Tension in the string