Energy

Energy:

ability to cause change

The energy in the flame melts the candle wax. This energy makes the matter in the candle change states.

You use energy to fold paper. Your energy changes the paper into a different shape.

Many ways that matter can change:

•Sheet of paper cut into pieces

•Baking soda and vinegar can be mixed together to make a new kind of matter

** These changes don’t happen by themselves. Energy has to be added to make the changes happen. Your energy cuts the paper and mixes the baking soda and vinegar. The Energy in the baking soda and vinegar makes the new kind of matter.

Thermal EnergyThermal Energy:

The energy that moves the particles in matter

Energy moves the particles in matter.

Review:

Solid: particles are close together and move back and forth in place.

Liquid: particles can slide past each other

Gas: particles fly off in all directions

HeatHeat:

The movement of thermal energy from one place to another

Warm cocoa on stove

Pour cocoa into a cool cup

You touch the cup, it feels hot

Thermal energy always moves from a hot place to a cold place. It never moves from a cold place to a hot place.

•The higher the temperature the faster the particles, or molecules, of an object are moving

HeatTemperature is really a measure of how much thermal energy an object has.

Campfire will give us both thermal energy but also light energy

Solar energy (sun) causes objects outside to become hot – our cars, the metal school playground equipment etc

Light

Uses of light:• light energy gives things colors;• helps plants make food and grow; •it can be used by cars to move instead of gas;• powers satellites and space stations; •doctors use light energy of lasers to perform some operations

Light travels in straight lines.(When you stand in the sun, you block some of the lines of sunlight – helps produce shadows)

Bouncing Light:Light travels in a straight line and hits the mirror. It now bounces off the mirror and is still traveling in a straight line, but only in a new direction. It is coming straight back to you. The bouncing of light off an object is called reflection. Light bouncing off a smooth surface gives you an image you can see. Most things are bumpy. When light hits a bumpy surface, each straight line of light goes off in a different direction and you don’t see any image.

Bending Light:Light travels at different speeds in air, water and glass. Any time light goes from one kind of matter to another, it changes speed. If light hits new matter straight on, it keeps going straight. But if light hits the new matter at a slant, the light bends. The bending of light when it moves from one kind of matter to another is called refraction.

Pencil or toy in the water: the top half you see through air and it appears normally. The bottom half you see through water and it appears to be somewhat bent. The light bends when it hits the water. Light travels slower through water.

SoundSound is created when an object vibrates. The vibration of the object pushes the air molecules nearby, which travel as sound waves to the listener.

Sound energy requires a medium such as air or water to transmit, which is why sound does not travel in space.

Sound can be made to be louder by blowing harder on a horn or recorder, striking a bell or beating a drum harder.

Mechanical

•Energy possessed by an object due to its motion or due to its position (energy found in machines)

Mechanical energy could come from movement and potential energy is the stored energy which comes from an object’s placement.

Examples of mechanical energy:• moving water such as river

•moving turbine such as those found in power plants

•moving object such as vehicles

Examples of mechanical energy:

•rotation and revolution of the earth

. walking and running

•objects that are falling (free fall)

•a flying aircraft or bird