ENERGY: A DEFINITION
ENERGY is the property of an object, (such as a brick), or a field, (such as a magnetic field), which allows it to do work that can be measured on another object or field. Energy is measured in joules (J).
FACTS ABOUT ENERGY
- TRUE: Energy is conserved; it cannot be created or destroyed.
This simple fact is one of the most important laws of Science. It is known as the Law of Conservation of Energy. - TRUE: The total amount of energy in the Universe stays the same ... this total amount
NEVER changes, (see above).
- TRUE: No process or event can happen in nature without energy being transferred.
MYTHS ABOUT ENERGY
- FALSE: Energy can be created.
- FALSE: Energy can be destroyed.
A USEFUL ANALOGY
Wealth is to the economic world - as energy is to the natural world. For example, wealth can take many forms. It may be in the form of cars, jewels, real estate, money in the bank, or potential earnings. Nothing in the economic world can happen unless money is transferred, (wealth is transferred). The currency of the economic world is the dollar.
Similarly, energy can take many forms. It may be in the form of kinetic energy, (heat and motion), gravitational or chemical potential energy, or even in the form of mass. Nothing in the natural universe can change unless energy is transferred. The currency of the natural world is the joule.
We can notice another very important similarity between wealth and energy when an event, such as the purchase of an automobile, occurs. We never actually see the dollars transferred. We simply assume the transaction has taken place based on the effects we observe, namely the new automobile owner driving the car off the car dealer's lot.
Similarly, when we observe a bowl of hot soup cooling down, we don't actually "see" joules of energy being transferred to the surrounding air, but we assume that this is happening based on the effects that we observe, (soup getting cooler and the surrounding air getting warmer).
SUMMARY
- Energy is a property or characteristic of an object, (or field), which can be measured, (in joules).
- Whenever anything happens, energy is transferred!
