Respuesta :

Newton's first law states that an object at rest will stay at rest && an object in motion will remain in motion unless acted on by another force. With that being said you feel tossed around because you are initially at rest but when you ride the roller coaster you take it's course of motion. 

Hoped this helped!

Explanation:

A roller coaster is hard to stop because it has a lot of inertia. Inertia can be simplified to, "objects want to keep doing what they are doing." It's when they are forced to do something different that they are doing that is why roller coaster riders experience the float or tossing around of the ride.