What Is Energy?

 

Energy is hard to define. We have lots of ways of explaining it, but none of them are ideal. We know that energy is a property of objects that can be moved from one object to another, and from one type of energy to another. We know that when things move fast, they have a lot of energy. And when things are put in a position where they definitely will move if released, they have potential energy. But it's unclear exactly what energy 'is.'

In physics, we define energy as the ability of a system to do work. It's like a currency that can be used to make things happen. And unfortunately, that's probably the best thing explanation that we have.

But one thing's for sure: objects can have energy, and that energy can be calculated. And when we make that calculation, we discover something interesting: we discover that energy is conserved. Conservation of energy says that energy isn't created or destroyed, it can only move from one object to another, or from one type of energy to another.

For example, if you take a pool shot the energy from your arm caused the cue ball to move, which after the collision caused the target ball to move (assuming you didn't miss!).

 

Types of Energy

 

But if energy can transfer from one type to another, the next obvious question is: What types of energy are there?

Well, there are a lot of types of energy. There's kinetic (or movement) energy, gravitational potential (or stored) energy, elastic potential energy, chemical energy, light energy, sound energy, nuclear energy, mechanical energy, heat energy and many more.

Kinetic energy is movement energy - faster moving objects have more of it. Gravitational potential energy is energy stored in objects that are high up. For example, when you lift a ball up in the air, you're giving it gravitational potential energy. Elastic potential energy is energy stored in stretched rubber bands and springs. Chemical energy is energy stored in food, or gas for your car, or the chemicals in batteries. Light energy is energy inside light and sound energy is the energy carried by sound waves. Nuclear energy is the energy stored in the atom. Mechanical energy is energy in turning joints, like your elbows and the wheels of bicycles. Finally, heat energy is energy in the form of hot, fast moving molecules, like in a boiling pot of tea.

These are all fundamentally the same thing, and energy can be changed from 

 

 

Energy Transformations

 

An energy transformation is the change of energy from one form to another. Energy transformations occur everywhere every second of the day. There are many different forms of energy such as electrical, thermal, nuclear, mechanical, electromagnetic, sound, and chemical. Because the law of conservation of energy states that energy is always conserved in the universe and simply changes from one form to another, many energy transformations are taking place constantly.

Examples of Energy Transformations:

1. A toaster transforms electrical energy into thermal energy.

2. A blender transforms electrical energy into mechanical energy.

3. The sun transforms nuclear energy into ultraviolet, infrared, and gamma energy all forms of electromagnetic energy.

4. Our bodies convert chemical energy from food into mechanical and electrical energy to allow us to move.

5. A natural gas stove converts chemical energy from burning into thermal energy used to cook food.

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