Download ENERGY

ENERGY
Above and beyond PE & KE
THE LAW:
• CONSERVATION OF ENERGY
• ∑ E1 =∑E2
• Energy cannot be created or
destroyed; it only changes form
• Energy in = energy out
• Heat, light and sound are
common forms of energy
transfer
Many types of Energy
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Mechanical (PE & KE)
Gravitational
Kinetic
Chemical
Nuclear
Electromagnetic
Thermal
Mechanical Energy
• A object that is able to do work
has mechanical energy
• Examples: Cars, trains, tractors,
hammers, etc
Kinetic Energy (KE)
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The energy of motion
KE=1/2mv2
Expressed as Joules (J)
Example: Book falling from shelf
Potential Energy (PE)
• Stored energy
• “The energy of position in a
force field”
• PE=mgh
• Example: Book on a shelf
• aka: gravitational energy
Thermal Energy
• When the amount of heat added
to a system and something
happens to the system, Thermal
Energy is to blame
• Expressed as ΔQ
• Example: Heat added to water
activates the water molecules,
increasing the KE of the system
Chemical Energy
• When certain chemicals
combine, energy is released
• Most important source of
energy right now
• Example: Combustion of
glucose (sugar) in our bodies
• C6H12O6 +6O2
+ 690 kcal/mole
6CO2 + 6H2O
Electromagnetic Energy
• Waves transporting energy from
one point to another
• Rapid variation of electric and
magnetic field
• Examples: radio waves,
microwaves, infrared radiation,
visible light, ultraviolet, x-rays,
gamma rays, etc
Electrical energy
• Energy due to the separation of
charges
• Example: electricity!
Nuclear Energy
• aka mass energy
• E= mc2
• Einstein first observed that
anything with mass has energy
• Unstable isotopes can be fused
or split thus liberating the
energy within
• Examples: Fission & fusion
Nuclear Energy (cont’d)
• An incredibly small amount of
mass has an incredibly large
amount of energy
• Energy=mass x speed of light
squared
• Speed of light = 3 x 108 m/s
• 50 grams of mass has potential
to level an entire city
Elastic/Spring PE
• http://www.sciencejoywagon.co
m/physicszone/lessonch/05work/
spring/speng.htm
PROBLEMS:
• http://127.0.0.1:26300/Principles
_of_Physics/07_Work,%20Energy
%20and%20Power/06/sp.html
• http://127.0.0.1:26300/Principles
_of_Physics/07_Work,%20Energy
%20and%20Power/07/sp.html
• http://127.0.0.1:26300/Principles
_of_Physics/07_Work,%20Energy
%20and%20Power/09/sp.html
From Chemical to
Mechanical
• Dry Ice Bomb
Electromagnetic to
Chemical
• Photosynthesis
Electromagnetic to
Mechanical
• Motor
Electromagnetic to
Thermal
• Heater
Chemical to
Electromagnetic:
Battery
Mechanical to
Electromagnetic
• Generator
• Windmill
Mechanical to Chemical
• Metabolizing food
Mechanical to
Gravitational
• Projectile Motion
Mechanical to Thermal
• Friction
Gravitational to
Electromagnetic
• Dam
Gravitational to Thermal
• Compression
Chemical to Thermal
• Combustion:
refers to the rapid oxidation of fuel
accompanied by the production of heat, or heat and light
Thermal to Mechanical
• Turbine
Thermal to Gravitational
• Temperature gradient:
atmospheric and oceanic
currents
Nuclear to Thermal
• Nuclear reactor