Answer:
the total kinetic and potential energy of its particles
Step-by-step explanation:
In every object, there are two types of energy which can be found inside them-Kinetic and Potential Energy. For example, a solid object placed on a stationary table has a potential energy due to the vibration of the molecules of the object.
As the object is moved across the table, it has kinetic energy. The combination of both energy is known as thermal energy. An increase in both energy leads to increase in the thermal energy of a given object.