CHAPTER 15 ENERGY

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CHAPTER 15 ENERGY
Lecture
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Originizzle Producshizzle
Time
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Section 1 Energy and Its Forms
Is energy a life form??? Maybe a blob of
something??? Can you touch it??? What do you
know energy as???
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• We usually relate energy with the CHANGES it
  causes
• Roar of an avalanche (sound)
• Movement of snow or dust particles (motion)

http//video.google.com/videoplay?docid-456819857
3561305762qavalanchehlen
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Energy defined the ability to do work. In other
words, energy is transferred by a force moving an
object through a distance
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Work and energy are closely related. When work
is done on an object, energy is transferred to
that object. Therefore, work may also be thought
of as a transfer of energy (remember back in
chapter 14 W f x d). Both are measured in
joules (J).
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• Two Forms of Energy
• Kinetic
• Potential

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• Kinetic Energy the energy of motion!
• The kinetic energy of any moving object depends
  upon its mass and speed.
• to calculate the KE (in joules, J) of any
  object, multiply ½ by the objects mass (m) in
  kilograms and the square of its speed (v) in
  meters per second.
• KE ½mv2

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Calculations
1.) Woody Woodpecker is flying at a constant
speed of 8.0 m/s and his mass is 0.87 kg. What
is Woodys kinetic energy?
m 0.87 kg v 8.0 m/s KE ?
KE ½ mv2 KE ½ (0.87 kg)x(8.0 m/s)2 KE
55.68/2 27.84 J
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Calculations
2.) Clayton Lee is flying out of a cannon at a
constant speed of 5.6 m/s and his mass is 81.0
kg. What is Clayton Lees kinetic energy?
Clayton
m 81 kg v 5.6 m/s KE ?
KE ½ mv2 KE ½ (81.0 kg)x(5.6 m/s)2 KE
2540.16/2 1270 J
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Potential Energy energy that is stored as a
result of position or shape. Two Types 1.)
gravitational 2.) elastic
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An objects gravitational PE depends on its mass,
height, and the acceleration due to gravity.
PE mgh Again, measured in joules (J)
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Calculations
A FHS student diver at the top of a 10.0 m high
platform has a mass of 50.0 kg. What is her PE?
m 50.0 kg g 9.8 m/s2 h 10.0 m PE ?
PE mgh PE (50.0)(9.8)(10.0) PE 4900 J
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Calculations
In the Funny Barnyard, the ____ kg animals climb
up to a total height of ____ m. What is the PE
of the animal just prior to launch?
m ____ kg g 9.8 m/s2 h ____ m PE ?
1st, you must figure out the kg and m, then PE
mgh
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Elastic Potential Energy is the PE of an object
that is streched or compressed. EXAMPLES 1.) 2.)
3.) 4.) 5.)
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• Forms of Energy
• mechanical the energy associated with the
  motion and position of everyday objects
• -examples

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2. thermal the total PE and KE of all the
sub-microscopic particles (atoms) in an object -
examples
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3. chemical energy stored in chemical bonds
when bonds are broken, energy is released -
examples
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4. electrical the energy associated with
electric charge. - examples
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5. electromagnetic a form of energy that
travels through space in the form of
waves. -examples
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6. nuclear the energy stored in atomic
nuclei. - example