A roller coaster car of mass 1:20 x 10 kg is initially at the top of a rise at point @. It then moves 38.8 m at an angle of 40.09 below the horizontal to a lower point (a) Find both the potential energy of the system when the car is at points A and B and the change in potential energy as the car moves from point @ to point , assuming y = 0 at point B potential energy at @ potential energy at B change In potential energy (b) Repeat part (a), this time choosing y = 0 at point @, which is another 15.0 m down the same slope from point B potential energy at @ potential energy at (@ change in potential energy Need Help? Read It