Internal Energy

Sum of all the microscopic forms of E.  
Sum of all Kinetic and Potential Energies of the molecules of a system.
U (or E)
Hyper Physics link

Does not include translation or rotation of body as a whole.
Cannot measure total.  Can only measure ΔU

	First Law Statements: - A thermodynamic system can store or hold energy.  This Internal Energy is conserved. - The internal energy of the universe is constant. - The change in the internal energy of the universe is zero. ΔUuniverse = 0 - The sum of energy changes in the system and surroundings is zero. ΔUuniverse = ΔUsystem + ΔUsurroundings = 0 - For an isolated system:        ΔUsystem = 0 - For a closed system:        ΔUsystem = q + w - For a closed system at constant volume with only PV work: ΔUsystem = qv