Derive First law of thermodynamics
When an amount of heat energy is supplied to the system, part of it enhances internal energy of the system and remaining is utilized by the system to do work".
Explanation: If ΔQ is heat supplied to the system by the surrounding, Δu is change in internal energy of the system and Δw is work done by the system on the surrounding.
Then according to first law of thermodynamics ΔQ = Δu + Δw