Energy
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4. The Law of Conservation of Energy

Energy is neither created nor destroyed.
Figure 6. 29. Nutritional information. Food energy in kcal and kJ

Energy can be transformed from one form to another or can be transferred from one body to another, but the overall energy does remain the same.


Units of energy

Many different units are used to quantify energy.

As with other physical quantities, many different units are associated with energy. For example, the SI unit, joule (J), calorie and kilowatt-hour are all units of energy.

Given a quantity of energy in one set of units, one can always convert it to another (e.g., 1 calorie = 4.186 joules).

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