1. The problem statement, all variables and given/known data A small ball is attached to a massless rod at one end. The other end is hinged such that the rod can swing freely in the vertical plane. Find the time taken by this system to rotate from horizontal position to vertical position. Length of rod = L Acceleration due to gravity = g mass of ball = m All surfaces are frictionless. 2. Relevant equations 3. The attempt at a solution Tangential acceleration of ball is gcosθ where θ is angle the rod makes with horizontal Tangential acceleration is equal to Lα where α is rate of change of angular speed So i have Lα=gcosθ I am unable to proceed further. what do i do?