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ENERGY. Question : Which would hurt more… Falling off your chair, or falling off of the roof…?. Ouch… So the same mass has more energy depending on how far it moves (distance). Question : Which would hurt more… Getting hit with a ping pong ball or a bowling ball moving at 30 mph?. - PowerPoint PPT Presentation
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ENERGY
Question:Which would hurt more…
Falling off your chair, or falling off of the roof…?
Ouch…
So the same mass has more energy depending on how far it
moves (distance).
Question:Which would hurt more…
Getting hit with a ping pong ball or a bowling ball moving at 30 mph?
Ouch…
So a different mass has more energy depending on how fast
it moves (force).
Energy & Work
• ENERGY is the ability to cause change, or do work.
• WORK is the transfer of energy through motion. In order for work to happen, a force must be exerted over a distance.
• W = (force) x (distance)
In order to understand energy, we need to understand work.
• amount of work depends on how much force, and how much distance.
BOOK
The force is the same; the distance is greater, so
there’s more work.
What’s another example of work?
Share your 3 examples from yesterday’s assignment.
Now, let’s talk about ENERGY....
2 Types of Energy
• There are two types of energy: Potential & Kinetic.
* Potential = Stored* Kinetic = Movement
VOCABULARY
• Potential: stored energy: ‘hanging out’• Kinetic: movement energy: ‘happening’
• Energy: the ability to cause change.
• Work: the transfer of energy through motion.
Understanding Check• Why do these people have potential energy?
Understanding Check• How do you know he has kinetic energy?
2 TYPES
• Kinetic: The ‘Happening Energy’…Motion
• Potential: The ‘Hanging Out Energy’…Stored
POTENTIAL ENERGY• Things have energy depending on where they are.
penny
Empire State Building
rockflowers
The penny has LOTS of potential energy; the building, rock, and flowers don’t.
POTENTIAL ENERGY• There are many types of potential energy.
• Gravitational (the falling rock)
• Chemical (food)
FORMS OF POTENTIAL ENERGY
• Chemical (food, gasoline)• Nuclear (fusion & fission)• Gravitational (position or place)• Stored Mechanical (stretched rubber
band)
EXAMPLES OF POTENTIAL ENERGY
Food Nuclear
HeightStored Mechanical
KINETIC ENERGY
• Remember, it’s the energy of movement.
• Lots of things move!
KINETIC ENERGY
Things have energy depending on how big they are and how fast and far they move.
Which has more kinetic energy?
KINETIC ENERGY
• Sound– Travels in waves, JUST LIKE IN THE OCEAN– Has to have something to travel through.
Energy traveling through AIR
KINETIC ENERGY
• Radiant, light– Also travels in waves– DOESN’T need anything to travel through
Sun
Earth
Energy traveling through SPACE
KINETIC ENERGY
• Electrical– When electrons move. Don’t worry about what
an electron is just yet! Just remember: lightning and electricity are kinetic
energy.
EXAMPLES OF KINETIC ENERGY
DancingSound
ElectricityLight
Law of Conservation of Energy
• No, this doesn’t mean ‘Turn the lights out!’
• It means: “Energy may change form but it can neither be created nor destroyed under ordinary circumstances.”
Law of Conservation of Energy
• Energy can change from potential to kinetic, and then back to potential again.
• You can’t ever make MORE of it and you
can’t destroy it…
…you can just change the way it looks, how it is stored, where it goes, or how it is transferred.
Law of Conservation of Energy
• This simply means that if one object is losing energy, something else must be gaining energy…
• The converse is; if an object is gaining energy, something else is losing it.
Law of Conservation of Energy
An example would be a hammer hitting a nail…
Potential energy in the hammer, kinetic energy swinging the hammer…
…then the energy is transferred to the nail in form of movement into a piece of wood.
Law of Conservation of Energy
An example would be a hammer hitting a nail…
The hammer doesn’t have much potential energy anymore since it is down.
It would take some kinetic energy to lift it back up, so that it would again have potential energy to swing back down.
Conservation of Energy
• This means that kinetic energy can turn into potential energy which can turn into kinetic energy which
can turn into potential energy which can turn into kinetic energy which can turn into potential energy
which can turn into kinetic energy which can turn into potential energy……..
Kinetic Potential
