Download Ch. 13 power point (energy)

Ch. 13
Energy
What is Energy
• Energy- The ability to do work or cause
change.
• Think of work as transferred energy.
• Think of power as the rate at which energy is
transferred or the amount of energy
transferred in a unit of time.
• Power= energy transferred/ time
Question
• What is power in terms of energy?
Two basic kinds of energy
• Kinetic and potential
• Kinetic energy is the energy of an object due
to its motion. (moving)
• Depends on the mass
And velocity.
- KE increases if mass
and velocity increases.
Calculating KE
• KE= ½ X mass X velocity squared.
• The velocity of an object will have a greater
effect on its kinetic energy.
• Ex. Doubling the mass will double the KE,
Doubling the velocity will quadruple its KE.
- We measure energy in Joules (J).
Question
• Which has a greater effect on an objects
kinetic energy? Mass or velocity
Potential Energy
• Stored energy that results from the position or
shape of an object.
• PE related to an objects height is gravitational
Potential Energy.
• GPE is equal to the work done to lift it.
• GPE = weight X height
• The more an object weighs or the greater the
height, the greater the GPE.
Question
• A skier weighs 500 newtons. If the ski jump is
40 meters high, what is the GPE.
• If the next skier weighed 600 newtons, would
they have a greater GPE?
Elastic potential energy
• This happens when an object gains PE by
stretching or compressing it.
Ex.
• An archer pulls back the arrow on a bow. The
bow now has PE.
• when the string is released it sends the arrow
flying.
Section 2, Forms of Energy
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Mechanical energy
Thermal energy
Electrical energy
Chemical energy
Nuclear energy
Electromagnetic energy
Mechanical Energy
• Energy associated with position and motion of
an object.
• Ex. Quarterback throwing a football.
• The QB transfers ME to the football.
• Combination of its own PE and KE.
• Ex. A thrown football’s ME is a combination of
its position above the ground and its motion.
• ME= Potential Energy = Kinetic Energy
Question
• What two forms of energy combine to make
ME?
Thermal Energy
• The total PE and KE of particles in an object.
• If the particles in the object are moving fast
the object will be hot. (lava)
• If the particles in the object are moving slow
then the object will be cold. (ice cream)
Question
• What happens to the particles in a scoop of
ice cream as it melts?
• What happens to the lava as it moves away
from the volcanoe?
Electrical Energy
• Energy of electric charges.
• Ex. Shock from a door knob, lighting, runs
through power lines, etc.
• Can be KE or PE.
Chemical Energy
• Is PE stored in the chemical bonds that hold
chemical compounds together.
• It is found in almost everything.
• When bonds in chemical compounds break,
new chemical compounds may form.
Nuclear Energy
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Stored in the nucleus of an atom.
Released during a nuclear reaction.
Nuclear Fission- occurs when a nucleus splits.
Ex. Nuclear power plants use fission reactions to
produce electricity.
• Nuclear Fusion- occurs when nuclei of atoms
fuse, or join together.
• Ex. This occurs in the sun, releasing tremendous
amounts of energy.
Electromagnetic Energy
• Energy that travels in waves.
• Ex. Sunlight, X-rays
• Have some electrical properties and magnetic
properties.