# Internal Energy

Written by Jerry Ratzlaff on . Posted in Thermodynamics

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