As a group…As a group…

How could you prove something is matter?

How could we test something like air to prove it is or is not matter?

EnergyEnergy

What is Energy?What is Energy?

Is the ability to cause change.◦A.k.a. the ability to do work.

There are two general types of energy known as ◦Kinetic ◦Potential

Energy Energy Energy exists in many forms.Energy can be moved from one

object to another.Energy can be changed from

one form to another.Energy cannot be created or

destroyed.

Potential EnergyPotential EnergyThe energy in matter due to its position or

the arrangement of its parts

Kinetic EnergyKinetic EnergyEnergy of a moving object, causing change

VideoVideo

http://www.youtube.com/watch?v=Ehx1P4adv6I

http://www.youtube.com/watch?v=qZ4FFWvZtyo

Forms of EnergyForms of Energy

Six Forms of EnergySix Forms of EnergyMechanical Chemical Electromagnetic

Heat/Thermal SoundNuclear

Mechanical EnergyMechanical EnergyEnergy that moves

objects from place to place

You use mechanical energy when you kick a ball or turn the pedals of a bicycle

Other examples include water flowing in a stream, tires rolling down a road and sound waves from your iPod.

Chemical EnergyChemical EnergyEnergy released by a

chemical reaction The food you eat

contains chemical energy that is released when you digest your meal

Wood, coal, gasoline, and natural gas are fuels that contain chemical energy

Electrical EnergyElectrical EnergyEnergy that comes from

the electrons within atoms It can be generated at a

power plant or inside a battery and can power everything from remote-controlled cars to refrigerators

Lightning and static electricity are also forms of electrical energy

Heat (Thermal) EnergyHeat (Thermal) EnergyEnergy created by

the motion of atoms and molecules that occurs within an object

Thermal energy exists when you heat a pot of water on a stove

Nuclear EnergyNuclear EnergyEnergy contained in the

nucleus of an atom Nuclear energy is released

when nuclei are split apart into several pieces, or when they are combined to form a single, larger nucleus

SoundSoundResults from the

vibration or particles in solids, liquids, and gasses.

We are able to detect these tiny vibrations with structures in their ears that vibrate due to sounds.

Law of Conservation of EnergyLaw of Conservation of EnergyWith every transformation, some energy is converted to less useful forms. Energy conversions are not 100% efficient. The energy output for the intended purpose is seldom the same as the energy we put in.

100 J electricity in95 J heat out

5 J light out!!!!

VideoVideo

Montage◦Science of Disney Imagineering, The: Energy

Energy ConversionEnergy Conversionand Efficiencyand Efficiency

What are we taking about?What are we taking about?

What is an energy conversion?How efficient are we?How do power plants work?How does a Hydroelectric dam work?How does nuclear energy work? How do

we split an atom?How does a nuclear power plant work?

What is an energy conversion?What is an energy conversion?

Energy conversion is where we take one type of energy and change it to another type, like from mechanical to electromagnetic.

In the process we get some energy that we intend. However some energy is lost to other sources.

Everyday Energy ConversionsEveryday Energy Conversions

We wake up and begin by eating breakfast. Electromagnetic to Thermal

◦ In order to cook food we turn on an electronic stove which produces heat.

Chemical to Mechanical ◦ We eat food, which has chemicals and our body converts

the chemical into forms we can use and when we move we create mechanical energy.

Electromagnetic to Sound◦ We walk out the door and put in your head phones, this

takes electrical energy from your phone and produces sound.

These are just a few conversions that occur before we walk out the door.

Unintended energy “loss”Unintended energy “loss”

Electromagnetic to Thermal◦ When we were heating our food, the burner glowed this

produced light in addition to heat.Chemical to Mechanical

◦ When we ate the food, we didn’t use all of the energy that was there and it becomes our waste products.

Electromagnetic to Sound◦ While you used your phone it listen to music your phone

also heated up, losing some of the stored energy.Efficiency is a measure of how much energy that

is put in turns out to be what we want it to be. In other words, how well do we use our energy.

Vehicle Efficiency – Vehicle Efficiency – Gasoline EngineGasoline Engine

25% Of the gasoline is used to propel a car, the rest is “lost” as heat. i.e an efficiency of 0.25

Efficiency of Some Efficiency of Some Common DevicesCommon Devices Device Electric Motor

Home Oil Furnace Home Coal Furnace Steam Boiler (power plant) Power Plant (thermal) Automobile Engine Light Bulb-Fluorescent Light Bulb -Incandescent

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Efficiency

How efficient are we?How efficient are we?

Humans have an efficiency of anywhere from 20-30%. That means only 20-30% of what we eat is converted into movement.

Remember unlike a car or phone, we have to be constantly “on” in order to survive. Even while sleeping our body is using energy for activities like breathing.

How do power plants work?How do power plants work?

How does a Hydroelectric dam How does a Hydroelectric dam work?work?

How does nuclear energy work? How does nuclear energy work? How do we split an atom?How do we split an atom?

http://www.pbslearningmedia.org/asset/nvhe_vid_fission/

How does a nuclear power plant How does a nuclear power plant work?work?

http://www.youtube.com/watch?v=vTHPQqOPg8E

Chapter 3 QuestionsChapter 3 Questions

1) Describe a stone falling off a tabletop in terms of both kinetic energy and potential energy.

2) Give an example of an energy conversion that produces unwanted forms of energy.

3) Describe a situation in which chemical energy is converted into mechanical energy. Explain each step of the energy conversion process.

4) Suppose that one air conditioner becomes very hot when it is working but another does not. Which air conditioner is more energy efficient? How can you tell?