As the forces on a roller coaster ride pull you up, down, and sideways, you might think the only thing keeping you in your seat is the lap bar or shoulder restraint.
Actually, the forces of speed and gravity are usually enough to keep you in place, says roller-coaster designer Alan Schilke. The restraints are there mostly to keep people from standing or jumping out of the cars.
The restraints do come in handy, though, when something goes wrong. Roller coaster cars have no power of their own. They're towed to the top of a hill by a chain or cable. As long as nothing gets in their way, they'll finish the course smoothly, letting gravity and speed keep them moving along the track.
Once in a while, a wheel will get damaged or jammed, and then the coaster slows down faster than it should. On a few rare occasions the cars have even gotten stuck upside down in the middle of a loop. Then the riders get a special thrill while they hang upside down, waiting to be rescued. In this case, they can be very grateful for the restraints that keep them in the cars!
But problems on a roller coaster are rare. The rails and cars are inspected daily, and the tracks are built to survive a major earthquake. As scary as the ride seems, you're actually quite safe.
So relax and enjoy the ride!