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What Is Energy?

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Energeia is the Greek word for energy, meaning in or at work.

Over time, energy has come to mean many things to us.  In physical science, energy means the ability to do work.  Work means a change in position, speed, state, or form of matter.  Therefore, energy is the capacity to change matter.

Everything we do involves energy.  Getting up, going to school, and doing chores require energy.  In fact, everything that happens in the universe, from the eruption of volcanoes, to the sprouting of seed, to the moving of people, takes energy.  When we turn on a motor, drive a car, cook on a stove or switch on a light, we are using energy.

Figure 1
Energy is everywhere

Everything that happens in the universe, from the sprouting seed to the eruption of volcanoes, involves energy.