19 Mar. 1983|
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Roller coaster history can be traced back to 16th century Russia where people rode sleds down ice covered slides. If you're studying physics, there are few more exhilarating classrooms than a roller coaster. The world's tallest and fastest roller coaster, the Kingda Ka at Six Flags Great Adventure in New Jersey. In the last few sections, we looked at the forces and machinery that send roller coasters rocketing around elaborate courses. Riders hang upside down on the Riddler's Revenge, a stand-up coaster at Six Flags Magic Mountain in California. As you go around a loop-the-loop, your inertia not only produces an exciting acceleration force, but it also keeps you in the seat when you're upside down.A roller coaster loop-the-loop is a sort of centrifuge, just like a merry-go-round.
There are two major types of roller coasters, distinguished mainly by their track structure.The tracks of wooden roller coasters are something like traditional railroad tracks.
Roller coasters are driven almost entirely by basic inertial, gravitational and centripetal forces, all manipulated in the service of a great ride. The direct ancestors of roller coasters were monumental ice slides -- long, steep wooden slides covered in ice, some as high as 70 feet -- that were popular in Russia in the 16th and 17th centuries. In most coasters, the car wheels have the same flanged design as the wheels of a train -- the inner part of the wheel has a wide lip that keeps the car from rolling off the side of the track. Don't be alarmed if you're getting on a loop-the-loop coaster with a lap bar -- as we saw earlier, inertia would keep you in your seat even with no restraints!The restraint system -- and everything else on a roller coaster -- is completely computer-controlled. Amusement parks keep upping the ante, building faster and more complex roller coasters, but the fundamental principles at work remain the same.In this article, we'll examine the principles that keep coaster cars flying around on their tracks. Riders shot down the slope in sleds made out of wood or blocks of ice, crash-landing in a sand pile.Coaster historians diverge on the exact evolution of these ice slides into actual rolling carts.
You experience this phenomenon all the time -- think about driving your car, riding your bike or pulling your sled to the top of a big hill. The constraining bar at the edge of the merry-go-round stops you from following this path -- it is constantly accelerating you toward the center of the platform.The loop-the-loop in a roller coaster acts exactly the same way as a merry-go-round.
In order to build an acceleration force strong enough to push the train into the track at the top of the loop, they had to send the train into the loop at a fairly high rate of speed (so it would still be going pretty fast at the top of the loop).
The potential energy you build going up the hill can be released as kinetic energy -- the energy of motion that takes you down the hill.Once you start cruising down that first hill, gravity takes over and all the built-up potential energy changes to kinetic energy.
The warmer climate of France tended to melt the ice, so the French started building waxed slides instead, eventually adding wheels to the sleds.
To build up this momentum, you need to get the train to the top of the first hill (the lift hill) or give it a powerful launch.Chain LiftThe traditional lifting mechanism is a long length of chain (or chains) running up the hill under the track.
There is no possibility that, say, the ride would leave the station with an unsecured safety belt or that an attendant would forget to apply the coaster's brake. In 1817, the Russes a Belleville (Russian Mountains of Belleville) became the first roller coaster where the train was attached to the track (in this case, the train axle fit into a carved groove). The chain is fastened in a loop, which is wound around a gear at the top of the hill and another one at the bottom of the hill. This way, you can send the train through the loop fast enough that it has an adequate acceleration force at the top of the loop, while the teardrop shape creates a reduced acceleration force along the sides. All coasters are carefully inspected on a daily basis and completely worked over during the park's off-season.Even armed with all these facts, you'll probably still be a little nervous. The French continued to expand on this idea, coming up with more complex track layouts, with multiple cars and all sorts of twists and turns.The first American roller coaster was the Mauch Chunk Switchback Railway, built in the mountains of Pennsylvania in the mid-1800s.
Your own outward inertia creates a sort of false gravity that stays fixed at the bottom of the car even when you're upside down. Just remember that roller coasters are designed to give you a thrill -- to make you feel like you're in danger, if only for a few seconds. You need a safety harness for security, but in most loop-the-loops, you would stay in the car whether you had a harness or not.As you move around the loop, the net force acting on your body is constantly changing. In wooden coasters, the exhilarating motion is mainly up and down.The range of motion is greatly expanded in steel roller coasters. So just sit back, relax and enjoy the ride!For much more information on roller coasters and related topics, check out the links on the next page.
Over the next 30 years, these scenic rides continued to thrive and were joined by wooden roller coasters similar to the ones we know today. At every point on a roller-coaster ride, gravity is pulling you straight down.The other force acting on you is acceleration.
The world of roller coasters changed radically with the introduction of tubular steel tracks in the 1950s. These coasters were the main attraction at popular amusement parks throughout the United States, such as Kennywood Park in Pennsylvania and Coney Island in New York. The same thing happens when you drive down a dip in the road in your car or descend in an elevator moving at high speed.On a roller coaster, this full-body sensation is complemented by all sorts of visual cues -- the upside-down turns, dizzying heights and passing structures. By the 1920s, roller coasters were in full swing, with some 2,000 rides in operation around the country.With the Great Depression and World War II, roller-coaster production declined, but a second roller-coaster boom in the 1970s and early 1980s revitalized the amusement-park industry.
At the summit, the chain dog is released and the train starts its descent down the hill.Catapult-launch LiftIn some newer coaster designs, a catapult launch sets the train in motion. When you ride a roller coaster, all of the forces we've discussed are acting on your body in different ways.Newton's first law of motion states that an object in motion tends to stay in motion. You feel the gravity pulling you into your seat, but (if your eyes are still open) you can see that the ground is no longer where it should be.At the top of the loop, when you're completely upside down, gravity is pulling you out of your seat, toward the ground, but the stronger acceleration force is pushing you into your seat, toward the sky. In addition to the traditional wheels that sit right on top of the steel track, the cars have wheels that run along the bottom of the tube and wheels that run along the sides. Some of the most popular ride variations -- such as the curving corkscrew track -- saw their heyday around this time.In the next section, we'll look at the coaster components that get the train rolling and bring it to a stop.
Instead of dragging the train up a hill to build up potential energy, these systems start the train off by building up a good amount of kinetic energy in a short amount of time.One popular catapult system is the linear-induction motor. Roller-coaster designers make sure to create plenty of tight fits and near misses to make you feel like you're rocketing through the structure at out-of-control speeds.One of the most exciting elements in modern coasters is the loop-the-loop. This design keeps the car securely anchored to the track, which is absolutely essential when the train runs through the coaster's twists and turns.The train cars in tubular steel coasters may rest on top of the track, like the wheels in a traditional wooden coaster, or they may attach to the track at the top of the car, like in a ski lift. As in the sharp descent, you are almost weightless for the brief moment when you are at the top of the loop.As you come out of the loop and level out, you become heavy again. If you've been consuming alcohol or if you don't meet the height and weight requirements, you are putting yourself at risk by riding a roller coaster. A wooden roller coaster rattles as it rolls over the joints that connect the pieces of the wooden track. The wheels grip the bottom (or top) of the train between them, pushing the train forward.The BrakesLike any train, a roller coaster needs a brake system so it can stop precisely at the end of the ride or in an emergency. As the train enters the loop, it has maximum kinetic energy -- that is, it is moving at top speed.
As any coaster enthusiast will tell you, each sensation has its own distinctive charm.According to the Roller Coaster DataBase, there were 2,088 coasters in operation around the world in 2007 -- 1,921 of them steel, 167 wooden.
At the top of the loop, gravity has slowed the train down somewhat, so it has more potential energy and less kinetic energy -- it is moving at reduced speed.