Question

this diagram shows an amusement park roller coaster ride.(a) on what part of the ride is the car moving slowest?(b)on what part of the ride is the car moving fastest?(c)The car become stuck at point p which is 50 meters above the ground.To the relief of the presenters the car eventually move again and passes point R at 20m/s.Approximately how height is point R?The car and its passengers have a combined mass of 700kg.​

Answer 1

KE + PE = constant conservation of energy

At 50 m KE = zero and PE = m g h

PE = 700 kg* 9.80 m/s^2 * 50 m = 343,000 Joules

PE + KE = 343,000 J

At point R

PE = 343,000 J - 1/2 * 700 kg * 400 m^2 / s^2 = 203,000 J

m g h = 203,000 J at point R

h = 203,000 J / (700 kg * 9.80 m/s^2 = 29.6 m height of point R

Check:

343,000 = 700 * 9.80 * 29.6 + 350 * 400 = 343,000

Adding PE and KE at point R