Definition:Energy/Unit

Definition

The SI unit of measurement of energy is the joule.

The CGS unit of measurement of energy is the erg.

The FPS unit of measurement of energy is the foot-poundal.

Joule

The joule is the SI unit of energy.

It is defined as being:

the energy transferred to (or work done on) a body when a force of $1$ newton acts on that body in the direction of the force's motion through a distance of $1$ metre

the energy dissipated as heat when an electric current of one ampere passes through a resistance of one ohm for one second.

Thus:

$1 \, \mathrm J = 1 \, \mathrm N \, \mathrm m$

\(\ds \)

\(\)

\(\ds 1\)

joule

\(\ds \)

\(=\)

\(\ds 10^7\)

ergs

Erg

The erg is the CGS unit of energy:

It is defined as being:

the energy transferred to (or work done on) a body when a force of $1$ dyne acts on that body in the direction of the force's motion through a distance of $1$ centimetre.

Thus:

$1 \, \mathrm {erg} = 1 \, \mathrm {dyn} \, \mathrm {cm}$

\(\ds \)

\(\)

\(\ds 1\)

erg

\(\ds \)

\(=\)

\(\ds 10^{-7}\)

joules

Sources

• 1964: Milton Abramowitz and Irene A. Stegun: Handbook of Mathematical Functions ... (previous) ... (next): $2$. Physical Constants and Conversion Factors: Table $2.1$ Common Units and Conversion Factors
• 1976: Ralph J. Smith: Circuits, Devices and Systems (3rd ed.) ... (previous) ... (next): Chapter $1$: Electrical Quantities: Definitions and Laws: Definitions: Table $1$-$2$: Important Derived Quantities
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): energy
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): energy