Transcript what is energy notes

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1. What is energy?
2. What is work?
3. Explain how the two are related?
4. What is kinetic energy?
5. Give an example of kinetic energy.
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1.
2.
3.
4.
5.
What is kinetic energy? Potential Energy?
What is mechanical energy?
Explain what is happening at each letter.
If the mechanical energy at C was 100J and
the potential was 50J, what is the kinetic
energy?
If the kinetic energy at D is 100J, what is
the potential energy?
Energy -
Work -
the ability to do work
occurs when a force causes
an object to move in the
direction of that force
• When one object does work on another,
energy is transferred.
Therefore work is a transfer of energy
1. Tennis player can do work on her racket
because she has energy.
2. Energy transfers from person to racket. The
racket gains the ability to do work on the
ball.
3. Racket hits ball, energy is transferred from
racket to ball.
Kinetic Energy -energy
of motion, dependent
on the mass and velocity
(speed) of an object
Energy depends on mass and velocity
(speed)
Kinetic
Energy
=
mv2
2
25 m/s
20 m/s
25 m/s
1 Which vehicle has the most kinetic energy?
2 Why? Greatest mass and high velocity
The big truck
3 Which vehicle has the least kinetic energy?
4 Why?
Lower mass and least velocity
Smaller
car on left
The faster something is moving the more
kinetic energy it has
The more massive something is the more
kinetic energy it has
Potential Energy -
stored energy, due to
position or shape;
“energy of position”
1) The energy it
takes to pull back
the bow is stored
until the bow is
released!
2) The energy is
then transferred
to the arrow.
•Potential energy depends on
the weight of the object and
its height above the earth’s
surface.
•It is effected by gravity!
Mechanical Energy -
the total energy of motion
and position of an object
(sum of the KE and PE)
MECHANICAL ENERGY = Potential energy + Kinetic energy
ME = PE + KE
• As potential energy increases, kinetic energy
decreases
• As potential energy decreases, kinetic energy
increases
• As potential or kinetic energy changes, mechanical energy
stays the same
Most roller coasters use potential energy stored by gravity on the first hill to provide the
energy for the rest of the ride. As the roller coaster goes down the hill, potential energy is
transformed into kinetic energy. At the bottom of the first hill, the roller coaster has the
highest speed. This is where the roller coaster has the most kinetic energy and very little
potential energy. An electric motor pulls a roller coaster car up the first hill by a chain. The
roller coaster car gains speed as it falls down to the bottom the first hill. The roller coaster
car then goes up a second smaller hill. Describe the energy transformations:
The __________________ energy in the wires are transformed into mechanical
energy by the motor. The mechanical energy of the motor is transformed into
_____________ energy of the roller coaster at the top of the first hill. As the roller
coaster falls, its ______________ energy is transformed into mostly ___________
energy at the bottom of the hill. As the roller coaster climbs to the top of the
second, smaller hill, some of its ___________ energy is transformed into
_______________ energy.
Potential Energy Gizmo:
http://explorelearning.com/index.cfm?method=
cResource.dspView&ResourceID=399
Pendulum Gizmo:
http://explorelearning.com/index.cfm?method=
cResource.dspView&ResourceID=390
1) When is the coaster’s potential
energy at its highest?
2) When is the coaster’s kinetic
energy at its highest?
3) What condition must be met for
the coaster to continue
moving after the first hill?
4) In theory, the mechanical energy
shouldn’t change at all, but in
reality it decreases a bit. Why?
Paragraph
•Pick an activity
•Explain how work, energy, kinetic and
potential are involved in the activity.
•Explain the final statement “when work is
done the same amount of energy is
involved.”
•Or you can draw a diagram and explain
the diagram in terms of the above
information.
Identify the following as having either potential or kinetic energy:
Coal
___________________________
Mrs. Pustay rolling down a hill
___________________________
Holding a ball before throwing it
___________________________
The ball flying through the air
___________________________
burning coal
____________________________
a lit match
___________________________
Mr. Saska swinging on a swing
___________________________
Humpty dumpty sat on a wall
___________________________
Humpty dumpty had a great fall
___________________________
A car traveling at 100 mph along a flat road ___________________________
A rubber band that has been stretched.
___________________________
A piano lifted to a second story window.
___________________________
Energy Box- Here is a list of all the different forms of energy
Thermal Sound chemical Light Electrical Nuclear
Using the letters next to the forms of energy in the “Energy Box” above write down
any of the forms of energy you think are involved with each statement. (You can use
more than one energy)
1. __________ A garden of vegetables growing.
5. ________ A passenger train
2. __________ A DVD player
6. ________ Eating a cheese steak hoagie
3. __________ A person playing the piano7. ________ Jogging
4. __________ The sun
8. ________ A Power Plant
Use the “Energy box” above to match each definition.
1. ____ Energy of moving electrons.
2. ____ Energy produced by the vibrations of electrically charged particles.
3. ____ Energy associated with the changes in the nucleus of an atom.
4. ____ Energy of a compound that changes as its atoms form new compounds.
•
____ Energy of an object’s particles vibrating.
•
____ Total energy of the particles that make up an object.
Answer:
1. When a nucleus of an atom is split (more, less) energy is produced than when you
eat a banana.
2. Microwaves, radio signals, DVD players, and lamps are all associated with what type
of energy.
3. What happens to the particles in a guitar string when you pluck it?
4. Why do you think the sun is the most important energy resource? Minimum of 2
sentences!
5. Give an example of one type of energy converting into another type. Minimum
of 2 sentences
Read your poem, break it down
and discuss/write how these are
related to different parts of the
poem:
Energy
Work
Kinetic energy
Potential energy
Mechanical energy
Be ready to present!