What is defined as the ability to do work?

Energy is defined as the ability to do work. In physics, work is performed when a force acts on an object and moves it over a distance. Energy is the capacity that an object has to perform work, whether it's in the form of kinetic energy (due to movement), potential energy (due to position), thermal energy (heat), or other forms.

The various forms of energy can be converted from one type to another, but they all fundamentally relate to the capacity to exert forces and move matter. This is essential to understand because energy is a core concept in engineering, allowing professionals to analyze systems, optimize processes, and create solutions that facilitate work being done efficiently.

Force, while related to energy, refers specifically to an interaction that causes an object to accelerate, and does not encompass the broader concept of work on its own. Heat, as a specific form of energy transfer due to temperature difference, also does not fully capture the concept of energy as a whole. Power, which measures how quickly work is done (or how fast energy is transferred), is relevant but is a derivative of energy and work rather than their definitions. Therefore, energy is the most accurate answer regarding the ability to do work.