What is the definition of energy in a physical context?

In a physical context, energy is best defined as the capacity to do work. This definition encompasses the various forms that energy can take, such as kinetic energy, potential energy, thermal energy, and others. Energy can be transformed from one form to another and is a key component in understanding how physical systems operate, from the simplest machines to complex biological systems.

When we say energy is the capacity to do work, we are referring to the potential of energy to cause a physical change or to perform tasks, such as moving an object, lifting a weight, or generating heat. This aligns with the foundational principles of physics, where energy is recognized as a conserved quantity, meaning it cannot be created or destroyed but can change forms.

The other concepts—such as the ability to create motion, the measure of force over time, and the power required to overcome gravity—describe specific aspects or implications of energy but do not provide as broad or fundamental a definition as energy's capacity to do work does.