Change in Internal Energy

This model shows us a demonstration of the **First Law of Thermodynamics**. The First Law of Thermodynamics states that **heat is a form of energy**, and the **thermodynamic processes** are therefore subject to the **principle of conservation of energy**.



The heat energy cannot be **created or destroyed**. *It can be transferred from one location to another and converted to and from other forms of energy*. If the gas is heated, energy is added to the gas molecules. We can observe the increase in average kinetic energy of the molecules by measuring how the temperature of the gas increases.



The same situation occurs when we compress a piston, when total internal energy of the gas is increased, molecules speed up their motion and we can also observe higher temperature. When the gas is compressed, energy is transferred to the gas so the energy of the gas increases due to work.