Transcript Lewis Energy types

ENERGY:
What do we
remember?
ENERGY
Where is energy found and when?
Energy is around you all the time
What is energy?
Ability to do work
When work is done, what happens to energy?
Energy is given off
What is the SI unit for energy?
Joules (J)
Energy has the same SI unit as what?
Work
What are the two states of energy?
What can you tell me about KINETIC
ENERGY?(KE)
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Greek = kinetikos = “moving”
Energy of motion/movement
Depends on mass and speed
KE = mv2
2
• ↑ speed = ↑ KE
• ↑ mass = ↑ KE
• Speed has greater effect than mass
What can you tell me about
POTENTIAL ENERGY (PE)
• Energy of position/shape
• Stored energy
• Gravitational Potential Energy (GPE)
– (GPE) = weight x height
–Nxm=J
MECHANICAL ENERGY (ME)
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Objects total energy of motion and position
ME = PE + KE
PE ↑ = KE ↓
PE ↓ = KE ↑
ME remains constant
Pendulum
8
Car on an incline
9
Energy can take different forms…
THERMAL ENERGY
• KE
• Total energy of particles (atoms and
molecules) that make up object
• ↑ movement = ↑ KE = ↑ temp. = ↑ thermal
energy
• Particles far apart have more energy than
particles close together.
Energy vs. Thermal energy
Least
energy
Particle movement
most thermal
energy
Amount of particles
Most
energy
CHEMICAL ENERGY
• PE
• Compound energy that changes arrangement
of atoms
• Stored in bonds between atoms
• Chemical rxn takes place
ELECTRICAL ENERGY
• KE
• Moving electrons back and forth through wire
or current
• Produced at power plants
SOUND ENERGY
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PE and KE
Energy of vibrations
Transmits energy to air
Carried through solids, liquids, and gases
Travels in waves
LIGHT/RADIANT ENERGY
• Not all light can be seen
• Vibrations of electrically charged particles
• Travels through waves and empty space
NUCLEAR ENERGY
• Produced from change of nucleus
• Two types
– Fission: splitting nucleus (electrical energy)
– Fusion: joining nuclei (sun)
• Uranium:
– stores a lot of PE
– energy used from nuclei being split
– generated at nuclear power plants
VENN DIAGRAM OF FORMS OF
ENERGY
KINETIC
ENERGY
POTENTIAL
ENERGY
THERMAL
CHEMICAL
SOUND
NUCLEAR
LIGHT/RADIANT
ELECTRICAL
ENERGY CONVERSIONS
• Transfer/change/conver
sion of energy from
one form to another
• Can be transferred
converted to more than
one form
Energy Conversions
“Breakfast is the most important meal of the
day.”
Eating
Chemical
Energy
Being active
Kinetic
Energy
Body temperature
Thermal
Energy
Energy Conversions
electrical
chemical
electrical
light
and
sound
electrical
light
and
thermal
electrical
kinetic
and
sound
electrical
kinetic,
thermal,
and
sound
Energy Conversions
Energy Conversions
Energy Conversions
Explain the energy conversions
below.
ENERGY AND MACHINES
• Machines make work easier by changing
– Size
– Direction
– or both
of the force required to do the work
• Machines transfer energy and convert energy
Why are energy conversions
important?
• It is useful for every day life.
– Ex. Wind used to cook a meal
• Efficiency
– Ex. Energy efficient light bulbs and appliances
WHERE DOES THE ENERGY GO?
• Energy is never lost but converted to other forms of
energy
• Hills and friction help to tell what happens to energy
• Energy is used to overcome friction
• Some of the energy is always converted to thermal
energy
Law of Conservation of Energy
• Energy can neither be created or
destroyed
• Closed system- well-defined group of
objects that transfer energy between
each other.
• Total amount of energy always the
same
• Ex. Roller coaster, light bulb
Perpetual motion machine
• Runs forever without additional energy
• Energy in = Energy out
• Will never happen because some energy
is turned into thermal energy.
REFERENCES
• http://www.glenbrook.k12.il.us/gbssci/phys/
mmedia/energy/ce.html
http://www.physicsclassroom.com/mmedia/energy/se.html