Potential vs. Kinetic Energy
The Correct Answer and Explanation is:
Correct Answer
Point W is the location of the greatest potential energy.
Point X is the location of the greatest kinetic energy.
Explanation
The movement of a roller coaster is a classic example of the conversion between two types of energy: potential energy and kinetic energy. The principle of conservation of energy dictates that, in an ideal system without friction, the total energy remains constant. It simply changes from one form to another.
Potential energy is the stored energy an object has due to its position or height. The formula for gravitational potential energy is directly proportional to an object’s height above a reference point. In the diagram, point W is the highest point on the track. Therefore, the roller coaster car at this position has the maximum amount of stored potential energy. At this peak, the car is typically moving its slowest, meaning it has the minimum amount of kinetic energy.
As the roller coaster car descends from the great height of point W, its potential energy is converted into kinetic energy. Kinetic energy is the energy of motion, and it increases with an object’s speed. The drop in height causes the car to accelerate, gaining more and more speed. When the car reaches point X, it is at the lowest point of the track. At this position, nearly all the initial potential energy from point W has been transformed into kinetic energy. This means the car is traveling at its maximum velocity, and its kinetic energy is at its absolute peak. Correspondingly, its potential energy is at its minimum at point X.
The ride continues this energy exchange. As the car climbs the next hill to point Y, its kinetic energy is converted back into potential energy. It slows down as it gains height. Point Y has more potential energy but less kinetic energy than point X. Then, moving from Y toward Z, it again converts potential energy to kinetic energy, speeding up once more.
