Internal energy calculator (ΔU = q + w)
First law for a closed system: internal energy change from heat and work in joules.
Calculator
How to use
First law
$$\Delta U = q + w$$
Use the same sign convention your textbook uses for work on the system.
When to use
- Piston, compression, and PV-work problems linked to heat.
Educational use only. Double-check values for labs, homework, and exams.