1. The problem statement, all variables and given/known data A smooth circular wire of radius a is fixed with its plane vertical. A small ring threaded on the wire is projected with speed u from the lowest point of the circle. Taking gravitational acceleration to be the constant g, calculate the potential energy and the kinetic energy of the ring. Assuming conservation of energy, show that the ring will describe complete revolutions if: u^2 > 4ga 2. Relevant equations I know all relevant circular motion and SHM equations but don't know where to begin. 3. The attempt at a solution I genuinely have no idea how to approach this problem. Any help will be much appreciated.