Читать книгу String Theory For Dummies - Andrew Zimmerman Jones - Страница 89

Potential energy is stored energy. Potential energy takes many more forms than kinetic energy and can be a bit trickier to understand.

A spring, for example, has potential energy when it’s stretched out or compressed. When the spring is released, the potential energy transforms into kinetic energy as the spring moves into its least energetic length.

Moving an object in a gravitational field changes the amount of potential energy stored in it. A penny held out from the top of the Empire State Building has a great deal of potential energy due to gravity, which turns into a great deal of kinetic energy when it’s dropped (although not, as demonstrated on an episode of MythBusters, enough to kill an unsuspecting pedestrian on impact).

It may sound a bit odd, talking about something having more or less energy just because of where it is, but the environment is part of the physical system described by the physics equations. These equations tell us exactly how much potential energy is stored in different physical systems, and they can be used to determine outcomes when the potential energy gets released.