35 The Roller Coaster

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You've bought your ticket and boarded the roller coaster. Now you're barreling down the track at 60 miles per hour, taking hairpin turns and completing death-defying loops. Your heart is in your throat and your stomach is somewhere near your shoes.

The only thing separating you from total disaster is a safety harness, but are you really in danger? The designers of the roller coaster carefully crafted this thrilling ride to be just that, but you're actually in less danger than you think.

You face a greater threat of injury playing sports or riding a bike than you do on a park ride. Amusement park rides use physics laws to simulate danger, while the rides themselves are typically very safe.

How do physics laws affect amusement park ride design? In this exhibit, you'll have a chance to find out by designing your own roller coaster.

Plan it carefully--it has to pass a safety inspection. You can also experiment with bumper car collisions.

Check the physics glossary to find out more about the terms used in this exhibit.

For many people, there is only one reason to go to an amusement park: the roller coaster. Some people call it the "scream machine," with good reason. The history of this ride reflects a constant search for greater and more death-defying thrills. What you may not realize as you're cruising down the track at 60 miles an hour is that the

coaster has no engine.

The car is pulled to the top of the first hill at the beginning of the ride, but after that the coaster must complete the ride on its own. You aren't being propelled around the track by a motor or pulled by a hitch.

The conversion of potential energy to kinetic energy is what drives the roller coaster, and all of the kinetic energy you need for the ride is present once the coaster descends the first hill.

Once you're underway, different types of wheels help keep the ride smooth. Running wheels guide the coaster on the track. Friction wheels control lateral motion (movement to either side of the track). A final set of wheels keeps the coaster on the track even if it's inverted. Compressed air brakes stop the car as the ride ends.

Roller coasters can be wooden or steel, and can be looping or nonlooping. You'll notice a big difference in the ride depending on the type of material used.

In general, wooden coasters are nonlooping. They're also not as tall and not as fast, and they don't feature very steep hills or as long a track as steel ones do.

Wooden coasters do offer one advantage over steel coasters, assuming you're looking for palm-sweating thrills: they sway a lot more.

Tubular steel coasters allow more looping, higher and steeper hills, greater drops and rolls, and faster speeds.

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