KWLQ

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KWLQ

• What is Energy?

K What do you know?
W What do you want to know?
L What did you learn?
Q What questions do you have?
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Notes Energy
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NOTES 98-101

• Energy is the ability to work.

• Work is done when a force exerted on an object
  moves that object some distance.

• Work is a transfer of energy

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Both work and energy are measured in joules.
Work energy is force times distance
Units are Newtons x meters or Joules
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Two Types of Energy

• Kinetic Energy
• Energy associated with motion
• Ex. Dropping the bowling ball.

• Potential Energy
• Stored energy
• Ex. Lifting a bowling ball to a height.

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Kinetic Energy 1/2mass X velocity squared
Kinetic Energy ½m x v²
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180000J
KE (½ 3600Kg) X (10m/s)²
Kinetic energy depends on the square velocity! So
at twice the speed the truck has 4 x the energy
If the truck has a mass of 3,600Kg and a velocity
of 10m/s, whats its Kinetic energy?
A more massive truck has more kinetic energy.
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Equation for Gravitational Potential energy

• PEgrav mass x gravity x height
• or
• PEgrav m x g x h

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Another type of Potential Energy

• Elastic PE
• PE associated with objects that can be stretched
  or compressed.

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Elastic Potential Energy
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Gravitational Potential Energy
50Kg
10 meters high
PEgrav mass x gravity x height
4900J
PEgrav 50Kg x 9.8m/s/s x 10m
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50Kg
Now calculate Kinetic Energy
Whats its velocity if it falls for one second?
Kinetic Energy ½m x v²
2401 J
KE (½ 50Kg) X (9.8m/s)²
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• Energy conversion a change from one form of
  energy to another form.

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Energy conversion cont

• Most forms of energy can be converted into other
  forms
• Example Mechanical energy (running water) can be
  converted into electrical energy (electricity)

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For example burning coal at an electrical power
plant converts chemical energy into heat. The
heat makes steam which turns turbines mechanical
energy to make electrical energy. The electrical
energy is converted back into heat (oven), light
(lights in the house), and mechanical energy (a
cars engine) when it is used.
Gas ? engine
photosynthesis
Food ? your body
Heat lamp or hair dryer
Oil ? electricity via power plant
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Conservation of Energy

• Law of Conservation of Energy when one form of
  energy is converted into another form of energy,
  no energy is destroyed in the process
• Energy can not be created or destroyed

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Different Forms of Energy

• Mechanical motion or position of an object
• Thermal total energy of the particles in an
  object (the more energy the more heat is given
  off)
• Chemical PE stored in chemical bonds (food)

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• Electrical energy caused by moving electric
  charges

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• Electromagnetic energy visible light,
  microwaves, x-rays, and uv light

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• Nuclear fission and fusion

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Power

• Power is the amount of work done in a given time.

Equation for power
Power work/time
or
Power force x distance/time
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Power cont..

• Units for Power

Joules/second or
Watt (w)
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Formation of fossil fuels

• In the earths crust, under distinct pressure,
  temperature and geological processes,
  nonrenewable energy formed from once living
  organisms.

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Common Types of Fossil Fuels

• Coal
• Oil (petroleum)
• Natural Gas

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• Fossil Fuels make good fuels because the energy
  stored in them is abundant and easy to release
  when heated.
• Methane            CH4             (gas)
• Ethane              C2H6           (gas)
• Propane            C3H8           (gas)
• Butane              C4H10         (gas)
• Pentane             C5H12         (liquid, found
  in gasoline)
• Hexane             C6H14         (liquid, found
  in gasoline)
• Heptane            C7H16         (liquid, found
  in gasoline)
• Octane              C8H18         (liquid, found
  in gasoline)
• Pentadecane       C15H32       (liquid, found in
  kerosene  and jet fuel)
• Tetracosane       C24H50        (liquid, found in
  lubricating oil)

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Some common uses of Crude Oil

• Solvents
• Fertilizers
• Pesticides
• Plastics
• Diesel fuel
• Jet fuel
• liquified petroleum gas
• plastics

• Kerosene
• Synthetic fibers
• Synthetic rubber
• Detergents

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Source Energy Information Administration