2 A 250 kg roller coaster passes point A at 12.0 m/s. A/K v = 12.0 m/s A 18.0 m B What is the speed of the roller coaster at point B at the bottom of the hill if 8 500 J of energy is transformed to heat during the journey? (7 marks) W A 45 kg child on a water slide passes point A at 8.3 m/s. A/K v = 8.3 m/s A 21 m B As the child descends from A to B, 3 600 J of heat energy is created because of friction. What is his speed at B? (7 marks)