Final answer:
The phrase "ability to do work" defines energy. Energy is the capacity to move matter against a force (like air into a tire) and is measured in joules. Heat capacity relates to energy's ability to raise an object's temperature.
Step-by-step explanation:
The phrase "ability to do work" is a definition of energy. Energy is fundamentally the capacity to cause changes; for instance, it can be transferred from one object to another, doing work in the process. When we talk about doing work, it involves moving matter against an opposing force. A clear example of this is when you inflate a bicycle tire: you are doing work by moving air into the tire against the surrounding air pressure.
Energy is measured in the International System of Units (SI) in joules (J). One joule equals the amount of work done when a force of one Newton is applied over a distance of one meter. In the context of heat, heat capacity refers to the amount of energy required to raise the temperature of an object by 1°C, and it's related to the concept of energy as the capacity to supply heat.