It's actually not easy to give a precise definition of energy that covers all of the situations in which it occurs. For our course, a reasonable way to think about it is that **energy is either motion, or the ability to produce motion**. (However, some forms of this motion, like random molecular motion associated with thermal energy produced by friction, may be difficult to see.)
It's actually not easy to give a precise definition of energy that covers all of the situations in which it occurs. For our course, a reasonable way to think about it is that **energy is either motion, or the ability to produce motion**. (However, some forms of this motion, like random molecular motion associated with thermal energy produced by friction, may be difficult to see.)
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There are two important types of energy we talk about: //**kinetic energy**//, which is the energy associated with objects currently moving in a particular direction, and //**potential energy**//, which is energy stored somehow in a system that could cause things to move in the future (like a compressed spring that could push a block and make it move). A third form of energy is //**thermal energy**//, which is associated with the random motion of atoms and molecules. Kinetic or potential energy can be turned into thermal energy, but thermal energy cannot easily be turned back into kinetic or potential energy.
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There are two important types of energy we talk about: //**kinetic energy**//, which is the energy associated with objects currently moving in a particular direction, and //**potential energy**//, which is energy stored somehow in a system that could cause things to move in the future (like a compressed spring that could push a block and make it move). A third form of energy is //thermal energy//, which is associated with the random motion of atoms and molecules. Kinetic or potential energy can be turned into thermal energy, but thermal energy cannot easily be turned back into kinetic or potential energy.
A really nice feature of energy is that **energy is a scalar**, not a vector. Energy is just a number without any direction associated with it, which means there are no //x// and //y// components and no trigonometry to worry about.
A really nice feature of energy is that **energy is a scalar**, not a vector. Energy is just a number without any direction associated with it, which means there are no //x// and //y// components and no trigonometry to worry about.