Energy Notes

Energy is the ability to do work and make things change

There are 7 key types of energy:

Mechanical Energy –

This is energy caused by movement. When you use this energy you are physically moving something .Some examples are pedaling a bike, rolling a ball, and swinging a bat

  • Mechanical Energy can be in one of two states:
  • Potential – this is stored energy - not in motion, like a baseball player waiting for the next play
  • Kinetic – this is energy in use - in motion, like a baseball player hitting the ball

Chemical Energy

This energy comes from a chemical change, or the breaking down of another substance – like food in your stomach, fuel from burningwood and gasoline, or the chemicals inside batteries

Sound Energy

This is an energy we can hear produced by vibrations

Thermal Energy (Heat)

This is the energy of moving particles in an object

Radiant Energy (Light)

This is a form of energy we can see that travels in waves

Electricity

This is a form of energy that is produced when electrons move from one place to another

Magnetism

This energy is a force that pulls across a distance

Transfer of Energy

Energy is not created or destroyed, but it can change from one form to another.

A light bulb changes electrical energy into radiant energy and thermal energy. / A drill changes electrical energy into mechanical energy when the drill bit turns. It also changes into sound energy and thermal energy. / When wood burns, chemical energy stored in the wood changes to radiant energy and thermal energy.
/ In this battery-powered electric car, the chemical energy from the battery changes into electricity. Then many energy changes take place. For example, the electricity changes into mechanical energy to control the windshield wipers, sound energy to work the radio, and radiant and thermal energy in the headlights.

Sound Energy

This is an energy we can hear produced by vibrations

Vibrations:

Sound begins as a vibration; all sound comes from some type of vibration

Vibration is caused by something moving up and down or back and force very quickly

Sound Waves:

Travel outward in all directions from the source of a sound

Sound waves have to have a medium to move through (like air)

How fast sound waves travel depends upon the medium

Volume:

This is how loud or soft a sound is

Volume depends on how much energy is used to make a sound

Focusing the sound energy in one direction makes it seem louder

Echo:

This is when the sound bounces off of the objects around it and bounces back to the source (reflects)

Some animals, boats, and submarines use echoes to locate where things are around them

Pitch – How high or low a sound is

Things that affect the pitch of string instruments and drums

/ High Pitch / Low Pitch
Faster vibrations / Slower vibrations
Shorter Strings or drums / Longer Strings or drums
Thinner Strings or skins / Thicker Strings or skins
Tight Strings or skins / Loose Strings or skins

Radiant Energy

This is a form of energy we can see that travels in waves

Radiant energy (light energy) is a form of energy that we can see. Some objects give off light, such as the sun, fireflies, and lamps. Most objects do not give off light and we see them only because light reflects off of them.

The sun is Earth’s main source of light energy. Plants use sunlight (solar energy) to make food during a process calledphotosynthesis.

Light travels in waves along straight lines from its source

When light hits an object it can…

  1. Reflect – it bounces off of smooth surfaces
  2. Absorb – doesn’t bounce off, instead turns to thermal (heat) energy

Light Colors = reflect light and objects stay cooler

Dark Colors = absorb light and objects get warmer

Objects light waves hit might be:

Transparent – objects that allow all of the light to pass through

Examples: Clear Windows, Water, and Plastic Sandwich Bags

Translucent – objects that allow some light to pass through

Examples: Waxed Paper, Newspaper, and Lamp Shades

Opaque – objects that allow no light to pass through and create shadows

Examples: Wood, Mirrors, and Concrete Walls

Light waves appear to bend as the waves move from one medium to another. This is called refraction. One example is a pencil in a glass of water.

White light is made up of all the colors of the rainbow.

The colors of the rainbow: ROY G. BIV

Red Orange Yellow Green Blue Indigo Violet

Electricity

This is a form of energy that comes from electrons moving.

The negative charge of the electrons is pushed away from other negative charges and pulled towards positive charges because opposites attractand like charges repel.

There are two main types of electricity:

Static Electricity –This is the buildup of electric charges on an object. This happens when electrons move from one object to another. If you rub a balloon on your hair, and lift the balloon, then your hair will be pulled towards the balloon. Your positively charged hair is attracted to the negatively charged balloon. You may even hear a crackling sound as the “extra” electrons on the balloon jump to your hair all at once.

Current Electricity– This is the constant flow of electrons in an electric current. Electric currents can flow through metal wires to run lights, televisions, and other items.

Conductors and Insulators

  1. Conductors- objects that carry the electric current, allowing it to flow easily through

Good conductors are – many metals like copper & silver

  1. Insulators- objects that stop the flow of electricity, and do not allow it to flow through

Good insulators are – rubber, glass, wood, and plastic

Circuits

To turn on an electrical device on or off, you have to open or close the circuit. In a closed circuit, electrons have a complete pathway to travel through. In an open circuit, you put a gap in it so that the electrons cannot flow through.

Series Circuit – The electrical devices are connected in one big loop. There is only one pathway for the electricity to flow along. Therefore, if one light bulb stops working the others will not be able to light.

Parallel Circuit – There is more than one pathway for the current to flow through – each bulb is individually wired. Therefore, if one light bulb stops working, the others will still be able to light.

Magnets

Magnetism is a force that pulls across a distance.

Poles - The areas of a magnet where the force of magnetism is the strongest. The poles are labeled north and south.

Opposite poles Attract (pull together)

Like poles Repel (push away from each other)

Magnetic Field – This is the area around a magnet where the force of magnetism can be felt. It is invisible, but you can sometimes see its effects. Iron filings are used in this picture to show the magnetic field.

Things Attracted to Magnets: metal pins, paperclips, nails, scissors, staples, steel

Things NOT Attracted to Magnets: wood, rubber, pencil lead (carbon), aluminum foil, copper pennies, glass

Electromagnet: A temporary magnet that is created by wrapping a wire around an iron object and allowing an electric current to flow through

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