A small mass slides along a smooth vertical, circular track of radius R.
What is the minimum velocity this mass must have at the bottom of the circle in order make it all the way around without losing contact with the track?
If it is only moving at 7/10 of this minimum speed, at what angle theta does it lose contact (point P in the figure indicates where contact, is lost) with the track?
What is the fractional change in the kinetic energy of the mass in moving from the bottom point on the track to where it loses contact?