1. 1. The problem statement, all variables and given/known data: How to calculate minimum time period 't' required to complete a vertical circular motion by a cone filled with water, so that the water doesn't fall? 2. Relevant equations: v^2 = gR * [ 3 + 2 cos (theta) ] obtained by applying law of conservation of energy. 3. 3. The attempt at a solution: I have found that v^2 = gR * (3 + 2 cos theta ). But the velocity varies with theta. So, how to calculate the time required to complete one revolution using variable velocity? Thanks!