How does Newton's Third Law relate to a rollercoaster?

Answer 1

Newton's second law (Force equals mass times acceleration, F = ma) deals with acceleration so it "takes effect" every time that the roller coaster speeds up, slows down or turns (horizontally or vertically).

Basically Newton's second law just says that the acceleration of an object is directly proportional to the net force applied to the object and inversely proportional to the mass of the object. Or, in other words, the harder you push the faster it speeds up and the bigger it is the slower it speeds up (or slows down - deceleration is an acceleration).

This means that in your roller coaster example, the object is the roller coaster and the force can be: The motors that start the coaster and lift it up hills. The brakes that slow it down. Gravity which pulls it down the hills. The rails and wheels which cause the roller coaster to turn around bends, etc. At each of these points, Newton's second law is at play, determining how much acceleration will result from the force applied to the roller coaster's mass.

Answer 2

When the roller coaster stops