Energy
How could you prove something is matter?
How could we test something like air to prove it is or is not matter?
As a group…
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
What is 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 Energy
The energy in matter due to its position or the arrangement of its parts
Kinetic Energy
Energy of a moving object, causing change
http://www.youtube.com/watch?v=Ehx1P
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Video
Forms of Energy
Six Forms of Energy
Mechanical Chemical Electromagnetic
Heat/Thermal Nuclear
Sound
Mechanical Energy
Energy 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 Energy
Energy 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 Energy
Energy that comes from the electrons within atoms
It can be generated at a power plant or inside a battery and can power everything from remotecontrolled cars to refrigerators
Lightning and static electricity are also forms of electrical energy
Heat (Thermal) Energy
Energy 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 Energy
Energy 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
Sound
Results 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 Energy
With 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.
95 J heat out
100 J electricity in
5 J light out!!!!
Montage
◦ Science of Disney Imagineering, The: Energy
Video
Energy Conversion and Efficiency
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 are we taking about?
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.
What is an energy conversion?
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.
Everyday Energy Conversions
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.
Unintended energy “loss”
Vehicle Efficiency –
Gasoline 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
Common Devices
Device
Efficiency
Electric Motor
Home Oil Furnace
Home Coal Furnace
Steam Boiler (power plant)
Power Plant (thermal)
Automobile Engine
Light Bulb-Fluorescent
Light Bulb -Incandescent
90
65
55
89
36
25
20
5
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 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?
http://www.youtube.com/watch?v=vTHPQ qOPg8E
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Describe a stone falling off a tabletop in terms of both kinetic energy and potential energy.
Give an example of an energy conversion that produces unwanted forms of energy.
Describe a situation in which chemical energy is converted into mechanical energy. Explain each step of the energy conversion process.
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?
