\[\Delta U = Q - W\]
Variables
dU[ΔU]change in internal energy (J)
Qheat added to the system (J)
Wwork done by the system (J)
Description
What is this formula?
The First Law of Thermodynamics states that the change in internal energy of a system equals the heat added to the system minus the work done by the system. It is a statement of energy conservation applied to thermodynamic processes.
When to use it
Use this formula when analyzing heat, work, and internal energy changes in closed thermodynamic systems. It is useful for gases, engines, compressors, pistons, and general energy balance problems.
Example
Given:
Q = 500 J
W = 180 J
Formula:
ΔU = Q - W
Substitution:
ΔU = 500 - 180
Result:
ΔU = 320 J
Applications
Heat engines, gas expansion, compression processes, piston-cylinder systems, thermal machines, energy balance calculations, and engineering thermodynamics.