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Is gravity a form of energy? If so, can other types of energy, e.g., kinetic or electrical, be converted into gravitational energy?
- Anonymous (age 14)
Sure. Think of tossing a ball up. It starts off with kinetic energy.
Then it goes up and slows down. At the top, it has less kinetic energy.
(None, if it's not going sideways.) Then it starts falling and has
kinetic energy again. When it was high up, the energy was in the form
of gravitational potential energy.
The energy you used to throw the ball up started out as chemical
energy, which came from the food you ate. Chemical energy really is a
form of electrical energy -- rearrangement of atoms to form different
molecules changes the amount of energy stored in electric fields in the
molecules (and perhaps a bit of kinetic energy too). You can trace the
energy in the food you ate back to sunlight, which is again
electromagnetic energy, which got its start from the nuclear fusion
processes in the sun -- these convert the potential energies of the
strong nuclear interaction into light (and a few other forms of energy
we cannot take advantage of, like kinetic energy of neutrinos).
Eventually a small bit of all of this gets converted into the
gravitational potential energy of that ball.
(republished on 07/25/06)
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