Consider a simple frictionless roller-coaster. It begins at x = 0, at a height of y = H. Then it drops into a dip, reaching a minimum at x = 100, with zero height (y = 0). Finally, it goes back up at x = 200, but only reaches a height of y = H/2. Assume the roller-coaster car starts from rest at x = 0. Which of the following statements are true?
A.The car's maximum gravitational potential energy occurs at the start, at x = 0
B.At the end, at x = 200, the car has only kinetic energy
C.Mechanical energy of the roller-coaster is not conserved because of the presence of the normal force
D.At the end, at x = 200, the car has the same total energy that it began with
E.In the middle of the dip, at x = 100, the car has both gravitational potential energy and kinetic energy
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