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Home > 4. Chemistry and Physics > Potential and Kinetic Energy
Podcast: 4. Chemistry and Physics
Episode:

Potential and Kinetic Energy
Category: Science & Medicine
Duration: 00:01:54
Publish Date: 2011-07-13 19:48:52
Description: Transcript: There are many situations in physics and astronomy where there is a mixture of gravitational potential energy and kinetic energy, or the energy of motion. An object in orbit around another object has both. In a circular orbit, there is one-half the amount of kinetic energy as the amount of gravitational potential energy, and both are constant through the orbit. In an elliptical orbit however, the amount of each type of energy changes continuously throughout the orbit. For example, in orbits in the solar system, or more particularly in the case of a highly elliptical comet orbit, the comet moves faster when it is closer to the sun. Thereby, its kinetic energy increases as its gravitational potential energy decreases, but the sum of the two remains constant. You can see these examples in more everyday situations right on the surface the Earth. When a ball rolls down an inclined plane, at the start, it has the maximum amount of gravitational potential energy and no kinetic energy, no motion. As it accelerates down the plane its gravitational potential energy decreases, and its kinetic energy increases. Or, consider a child on a swing. At each end of the swing the child is momentarily stationary and has no kinetic energy but is raised at the maximum height above the Earth’s surface and so has the maximum gravitational potential energy. As the child moves through the arc of the swing the kinetic energy increases, and the gravitational potential energy decreases until at the opposite end of the swing. Once again kinetic energy goes to zero, and gravitational potential energy is at maximum.
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