I really don't understand this: Consider a frictionless, 12000-kg roller coaster that starts at rest at the top of a hill, point A, 95 m high. It goes all the way the 75 degree steep hill and coasts horizontally (for an unspecified distance) before reaching point B (0 m high). The entire ride lasts 10 seconds and breaks engage with a constant force during last 4 seconds. Calculate: a) the constant breaking force that must be applied to bring the roller coaster to a stop at point B. b) the work being done by breaks to bring the roller coaster to a stop at point B. I don't understand the question at all. The wording is weird. How would I start this? I have no clue what so ever.