The term 'ability to do work' can be summarized as having the capacity for ENERGY. This is a concept that has been studied in physics, where it is defined as the capacity to do work or produce change. ENERGY is the ability to cause change in matter, and it can be measured in joules. It is also related to the concept of power, which is the rate at which work is done. In everyday life, ENERGY is used to power machines, vehicles, and other devices.