The ball has a mass m and is attached to the cord of length l. The cord is tied at the top...

The ball has a mass m and is attached to the cord of length l. The cord is tied at the top to a swivel and the ball is given a velocity v0. Show that the angle θ which the cord makes with the vertical as the baH travels around the circular path must satisfy the equation  Neglect air resistance and the size of the ball.