What is the definition of energy?

Energy is fundamentally defined as the ability to do work. In physics, work is defined as the transfer of energy that occurs when a force is applied over a distance. This means that energy enables systems to perform tasks, such as moving an object, generating heat, or powering machinery. Various forms of energy include kinetic energy, potential energy, thermal energy, and many others, all of which can be transformed from one type to another while still adhering to the principle of conservation of energy, which states that energy cannot be created or destroyed, only transformed.

The other options relate to different concepts within physics but do not capture the broad definition of energy. Resistance to changes in motion pertains to inertia and mass, while applying a physical force to an object refers to the concept of force itself. The ability to transfer heat describes thermal energy and heat transfer rather than the overarching definition of energy itself. Therefore, the best definition of energy, in this context, is its role as the capability to perform work.