A roller-coaster car with a mass of 650 kg starts at rest from a point 28 m above the ground. At point B, it is 14 m above the ground. [Express your answers in kilojoules (kJ).]
(a) What is the initial potential energy of the car?
1 . kJ
(b) What is the potential energy at point B?
(c) If the initial kinetic energy was zero and the work done against friction between the starting point and point B is 28000 J (28 kJ), what is the kinetic energy of the car at point B?