Roller coasters are very safe and are always designed by professionals. There are many safety measures included on each one to ensure that everyone has a safe and fun time riding the coaster. One of these measures helps the coaster with its motion. These are the wheels. For steel coasters, the trains have three sets of wheels to allow the train to move. One set is on top, which allows for the primary motion of the car. Another set is on the outside of the track to keep the train from moving across the tracks and falling off. The third set is on the bottom of the track to keep the train from falling off during inversions.
Roller coasters are able to move because of the energy that is built up from their first ascent. The first hill allows the train to build up potential energy. Potential energy is equal to the mass of the train, multiplied by gravity and the height of the hill, Ep=mgh. The higher the hill, the more potential energy that it will have built up to be transferred into the energy of motion, kinetic energy. Kinetic energy is equal to one half times the mass of the train times the velocity squared, or Ek=1/2mv^2. Since energy is always conserved, potential energy must roughly equal the kinetic energy. Friction between the wheels and the track make up the difference in that equality. Therefore, the first hill is very important in giving the train the speed that everyone is looking for, since speed is the positive velocity value.
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