Hmm I thought I was pretty good at this stuff but I guess not. I'd really appreciate it if someone could show me how to solve this problem. Does it involve anything more than work, power, and energy concepts? http://img205.imageshack.us/img205/7159/presentation19ai.jpg [Broken] A small mass m slides without friction along the looped apparatus shown. If the object is to remain on the track, even at the top of the circle (whose radius is r), what minimum height h must it be released?