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The purpose of roller coaster rise is to build up potential (stored) energy. As the roller coaster gets higher, there is a greater distance that gravity can pull it down. The potential energy that is built going up the track can be released as kinetic energy, as soon as the it starts drifting down the track. The faster the roller coaster goes, the more kinetic energy it has. Kinetic Energy is the energy which an object possesses as a result of being in motion.
The energy attributed to motion is equivalent to the quantity, (.5)mv2. This expression only involves the mass and speed of the object. This expression of the object is known as "Kinetic Energy." Kinetic Energy is a scalar and is measured in Joules when mass is in kilograms and speed is in meters per second.
For example, a 100 kg roller coaster travels at a constant speed of 4.6 m/s around a track which is 20 m across. What is its kinetic energy?
Ek = (.5)mv2
Ek = (.5)(100)(6.4)2 = 2048 J
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