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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.
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
an atom.
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=
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
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
• nuclear fusion
• http://www.pbslearningmedia.org/search/?
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
•