# What is the first law of thermodynamics?

Conservation of Energy

The first law of thermodynamics is essentially that energy cannot be created or destroyed, but only transferred into or out of a system. Stated in other terms:

The increase in the internal energy of a thermodynamic system is equal to the amount of heat energy added to the system, less any energy expended or transferred (as through work).

For example, if a cold object is put in contact with a hot object, the hot object will transfer heat (energy) to the cold one. The amount of energy lost by the hot object is equal to the amount of energy gained by the cold one.

That's the same as Conservation of Energy.

The "First Law of Thermodynamics" is the same as the "Law of Conservation of Energy". It means that there is a thing called energy, which can't be created or destroyed. The total amount of energy in the Universe doesn't change.

The First Law of Thermodynamics is also known as Conservation of Energy.

The first law of thermodynamics is simply the general law of conservation. We know that internal energy of U of a system can change through two modes either heat or work. This equation is the first law of thermodynamics dQ = dU + dW .