Internal Energy Store - GCSE Physics Definition

In the context of GCSE Physics, the 'internal energy store' refers to the total energy contained within a system due to the kinetic and potential energy of its particles. It encompasses the motion of the particles, which contributes to the system's thermal energy, and the energy associated with the forces between them. This is particularly important when considering changes in the system's state, such as melting or boiling. The internal energy store changes when energy is transferred to or from a system, like heating a substance, which increases the kinetic energy of its particles, raising its temperature. Another example is compressing a gas, which happens when work is done on a system.