# Definition:Energy

## Definition

Energy is a property of physical bodies which can be defined as the ability to do work.

Like time, it is difficult to define exactly what energy actually is.

### Symbol

The usual symbol used to denote the energy of a body is $E$.

### Dimension

The dimension of measurement of energy is $\mathsf {M L}^2 \mathsf T^{-2}$.

This derives from its definition as:

${\text{Force} } \times {\text {Distance} }$

### Unit

The SI unit of measurement of energy is the joule $\mathrm J$.