Question

What is first law of thermodynamics?

Answer 1

The "First Law of Thermodynamics" is a version of the law of conservation of energy

It applies to old-style-stated versions of a thermodynamic system:

`underbrace(Delta U)\_("change in internal energy ") =underbrace(Q_("in"))\_("heat added") + underbrace(W_("on"))\_("work done on system")`

As with all things thermo-dynamical, you have to dig a bit deeper to understand what that really means.