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energy
the ability to do work
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When work is done on an object, energy is
transferred to that object. Work is a transfer
of energy
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The major forms of energy are mechanical
energy, thermal energy, chemical energy,
electrical energy, electromagnetic energy, and
nuclear energy
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The energy associated with the motion and
position of everyday objects is mechanical
energy
◦ We will study forces and motions next
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thermal energy
the total potential and kinetic energy of all
the particles in an object
◦ We will study this month
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Chemical energy is the energy stored in
chemical bonds.
◦ We just got done studying chemical reactions!
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Electrical energy is the energy associated with
electric charges.
◦ We will do a little electricity in may
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Electromagnetic energy is a form of energy
that travels through space in the form of
waves. Visible light and X-rays are examples
of electromagnetic energy
◦ We will do a little light energy 4th quarter
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The energy stored in atomic nuclei is known
as nuclear energy.
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Comparing energy, we subdivide it into two
categories.
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The energy of motion is called kinetic energy
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KE=1/2mv2
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A 70.0-kilogram man is walking at a speed of
2.0 m/s. What is his kinetic energy?
A 1400-kilogram car is moving at a speed of
25 m/s. How much kinetic energy does the
car have?
A 50.0-kilogram cheetah has a kinetic energy
of 18,000 J. How fast is the cheetah running?
(Hint: Rearrange the equation to solve for v.)
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Potential energy is energy that is stored as a
result of position or shape.
Potential energy that depends upon an
object's height is called gravitational potential
energy.
PE=mgh
G=gravity, 9.8 m/s2
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A 60.0-kg person walks from the ground to
the roof of a 74.8-m-tall building. How much
gravitational potential energy does she have
at the top of the building?
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