Energy

Energy

What is energy?

Energy is the ability to cause change or do work.  If something changes, energy is being used.  If you are doing work, energy is being used.  Here's a short video:

Forms of Energy

There are many different forms of energy.  Light energy, heat energy, electrical energy are three common forms of energy.  Sound energy is also another type of energy.

Heat can be produced by rubbing objects together

Heat energy is one form of energy.  Heat energy can be produced in different ways.  One way to produce heat energy is by rubbing objects together.  Friction is when two objects rub together.

There are two other ways to produce heat energy.  Burning and Mixing are the two other ways to produce heat energy.

Light travels in straight lines

Light is another form of energy.  It is important to know that light energy always travels in straight-line paths.  Light energy always moves from one place to another in a straight line.

Light also gives off heat

Another important thing to know about light energy is that light energy also gives off heat energy.  If you have ever put your hand close to a light bulb, you know that the bulb feels hot.  It feels hot because the light energy is also giving off heat energy, which you feel as the warmth of the bulb.

Light can be reflected, refracted, and absorbed

Finally, light can be reflected, refracted, or absorbed.

Reflection is when light hits an object and bounces back off the object and in the direction it came from.

Refraction is when light changes direction.  This usually happens when a beam of light goes through water.  It changes its direction a little bit.  This makes objects look different if you look at them through water.

Absorption is when light goes into an object.  Some light energy hits an ojbect and goes into it.  This is why objects have color.  If an object looks green, the green part of light went into that object.  If an object looks red, the red part of light went into the object.