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Name:  Katie
Status:  student
Age:  14
Location: N/A
Country: N/A
Date: 2000-2001


Question:
How does velocity and motion work together in a roller coaster? How do rollercoasters work?


Replies:
Katie-

Without going into all sorts of heavy detail that would require a course in physics, here are the basic of a simple out and back roller coaster. There are other track designs, such as looping and shuttle, but we will keep this simple. Other kinds of coasters include tower drops and water rides.

The train is taken up the lift hill by a chain. (Some roller coasters now use magnetic impulse to get the train going). The energy flow is as follows: from the electric field into the mechanical turning of the motor driving the chain. As the chain lifts the train, the kinetic energy of the motion of the chain is given to the train. This energy, in turn, flows into the gravitational field. When the coaster makes it to the top of the lift hill, the chain disengages. The train is usually moving very slowly, here, about 1 - 2 meters per second. At this point, the maximum amount of energy for this cycle of the ride is stored in the gravitational field.

As the train begins to fall, the kinetic energy (motion of the train) increases as the gravitational potential (gravitational field) energy decreases. At the bottom of the first hill (most coasters), the velocity (and kinetic energy) are the greatest, and the gravitational potential energy is spent. As you climb the next hill, most of the kinetic energy is transferred to the gravitational field. The velocity decreases. And so it goes, on and on, during the ride's journey, the flow of energy between the motion of the train and the gravitational field.

I said most of the energy interplays back and forth, but not all. There is friction (wind resistance, track friction, etc.) causing some thermal heating. Because of this, all hills after the first are successively shorter. Ultimately, all of the gravitational and kinetic energies the train had at the top of the lift hill move into thermal energy by the end of the ride. This energy is now unavailable to the roller coaster system. Essentially, roller coasters are heaters, allowing for the flow of electrical energy into heat, by way of kinetic energy (motion) and the gravitational field.

As for the second part of your question, there are three sets of wheels, top, bottom, and side. The top wheels are referred to as the rollers, the bottom as up-stop, and the side wheels as the guides. They may be made out of any number of materials, including steel and neoprene. If plastics are used, the coaster is electrically grounded just before it goes through any proximity sensors so as not to short out the sensors. That is why you may see some sparks at night on some roller coasters. Designers usually shield these areas, so that park guests do not think the ride is on fire.

The tracks are steel, but the structure may be steel or wood (and on water rides, fiberglass or concrete). Steel coasters tend to be very smooth, while wooden coasters have many sub-accelerations between supports, giving the illusion of being rickety.

There are many kinds of braking systems. A common one has a fin of steel hanging from the center of each car. The brake pads are between the tracks. As the fin passes through the pads, the fins are squeezed to slow the train. If the pads are open, the coaster passes freely through.

There is lots more, including safety training of the operators, safety checks, maintenance, proximity sensors, psychology and physiology of fear, physiology of forces on the body, shape of track (parabolic, speed bumps, banking of turns, clothoid loops), visuals, sound, jerkiness, rotations, capacity, etc.

I hope this helps you!

Nathan A. Unterman



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