Define the first law of thermodynamic with one example.

See explanation below.

Step-by-step explanation:

The first law of thermodynamic states that heat is a form of energy, and as such, is subject to the principle of conservation of energy (Energy is not destroyed or created but remains constant)

For example, when you put an ice cube in water, the ice will melt but the water will get colder, this is because the temperature between the ice cube and the water tends to an equilibrium and the total heat in the system remained the same during this time.