Hey there! I'm having trouble with the following problem and I will appreciate it very much if you could help me out. A rollercoaster with mass m slides frictionless off a path with initial height h. At a certain point it makes a looping with radius r. http://img522.imageshack.us/img522/8781/looping9xj.th.gif [Broken] a) Give an expression for the height h if the rollercoaster just makes the looping. b) For safety reasons the height is chosen in such a way, so that it is 3/2 of the size of the minimum height. What's the velocity of the rollercoaster in the highest point of the looping? c) In which direction is the acceleration pointing in the highest point of the looping when the track is given the restrictions of question b? And what's it's magnitude?