# Internal Energy

Internal energy, abbreviated as U, is the total of all energies associated with the motion of the molecules in the system.

## Internal energy formula

\(\large{ U = \frac {3}{2} \; n \; R \; T_a }\) |

### Where:

Units |
English |
Metric |

\(\large{ U }\) = internal energy | \(\large{Btu}\) | \(\large{J}\) |

\(\large{ T_a }\) = absolute temperature | \(\large{ R }\) | \(\large{ K }\) |

\(\large{ R }\) = ideal gas constant | \(\large{ \frac{lbf-ft}{lbmol-R} }\) | \(\large{ \frac{J}{kmol-K} }\) |

\(\large{ n }\) = number of moles | \(\large{dimensionless}\) |

Tags: Equations for Energy