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Chapter 4 – ENERGY
Energy
Energy—The ability to cause change and the
ability to do WORK
9 Main forms of energy:
– 1. Electrical: energy due to moving
electrons
– 2. Chemical: energy stored in bonds
between atoms
– 3. Thermal: energy from heat
– 4. Radiant = Light: energy from the sun & light
– 5. Nuclear: energy stored in the nucleus of an atom
– 6. Sound: energy of vibrating sound waves
– 7. Magnetic: energy of magnetism
– 8. *Mechanical: Energy due to position and motion
• Kinetic + Potential= Mechanical
9. Elastic potential
Energy: Energy that is
stored in something that
stretches or compresses,
such a rubber band or
spring.
Kinetic Energy
• KE is energy of motion.
• KE = 1×m×v2
2
•
– m = mass (kg)
– v = velocity (m/s)
• SI Unit for Energy is Joule (J)
–Joule = kgxm2/s2 (This is NOT an equation—
just another way to write the unit)
Calculating Kinetic Energy
• What is the kinetic energy of a 44 kg
cheetah running at 31 m/s?
• KE = 1 m v2
•
2
• KE =
https://www.youtube.com/watch
?v=AO117teuR2Q
• Bill Nye Energy:
• On the back of your paper:
• Name as many examples of energy as you can
from the video.
• Name examples of energy changes in the video.
• http://glencoe.mheducation.com/sites/007
8778360/student_view0/brainpop_movies.
html#
Forms of energy overview
Potential Energy (PE)
• PE is energy that is stored in an object.
4 types of PE:
1. Elastic PE
– Energy due to a stretch (rubber band) or
compression (spring)
2. Chemical PE
– Energy in the bonds between atoms (foods &
fuels)
3. Gravitational PE
– Energy due to an elevated position
– GPE = m×g×h
• m = mass (kg)
• g = gravity=9.8 m/s2 (on Earth)
• h = height (m)
4. Nuclear energy: Energy stored in the nucleus of
Calculating Potential Energy
• A 65 kg rock climber
ascends a cliff. What
is the climber’s GPE
35 m above the base
of the cliff?
• GPE=
•
•
Kinetic Energy
Watch this BrainPOP animated movie explain how the
energy of motion changes depending upon an object's
speed and mass.
Potential Energy
In this BrainPOP movie, Tim and Moby show how potential
energy changes depending upon an object's position and
condition.
https://www.youtube.com/watch
?v=AO117teuR2Q
• Bill nye energy 22
min
• Bozeman science
KE PE
• https://www.youtub
e.com/watch?v=BS
Wl_Zj-CZs
Law of Conservation of Energy
L.o.C.o. Energy-• Energy can not be created or destroyed, it
just changes form.
•
•
•
•
Rollercoaster
mass and spring
Circus physics: transforming energy 2 min.
http://www.pbs.org/opb/circus/classroom/circ
Mechanical Energy
• Energy can be converted from Potential to
Kinetic, but the total energy doesn’t change
• Total Mechanical Energy = Kinetic + Potential
• ME = KE + PE
Nuclear Energy
• There are two types of nuclear energy
• Fission and Fusion
• Both forms energy are stored as mass in
the atoms of certain elements. This mass
can be changed into energy under the
proper conditions according to Albert
Einstein's famous equation:
•
•
nuclear fission
http://www.pbslearningmedia.org/resource/nvhe.sci.chemistry.fission/afission-chain-reaction/
nuclear fusion
http://www.pbslearningmedia.org/resource/phy03.sci.phys.matter.fusionbom
b/fusion-the-hydrogen-bomb/
Fusion & Fission
• Fusion atoms are "fused"
together
• In fusion lighter elements
form heavier elements
• Uses
• Fission the 2nd form of nuclear
energy
• The exact opposite of fusion.
• In fission atoms are broken apart.
• In fission heavier elements form
lighter elements.
• Uses
– Hydrogen Bomb
– Nuclear Energy Plants
– The middle of stars
Rube Goldberg
Unbelievable Rube Goldberg Machine - Google Video
•