How do rollercoasters work?

Answer 1

The chain lift at the beginning part of the ride lifts it up over the edge. Then with speed the train is basically on it's own. Not all Roller Coasters run on chain lifts. Some get launched like a sling shot such as Top Thrill dragster at Cedar Point. Some get lifted with an elevator like Millennium Force also at Cedar Point.
The roller coaster slows down with a magnetic part of the track. So that's mainly how Roller Coasters really work.

they use gravity=)

Answer 2

AnswerRollercoasters work because of fat peoples weight pulling it down due to gravity and their weight... havent you seen they always have a fat person on ther rollercoasters