Do Now:
What does it mean when you
say “That person has a lot of
energy”?
ENERGY
What have we learned so far?
1. Work is done on an object
when a force acts in the
direction the object is
moving.
2. When...
Power is the rate at which work is done.
• A tornado and a calm
breeze each do the
same amount of work
if they transfer th...
If energy is transferred when work
is done, then what is energy?
Energy is the ability to
do work!
We talk about ENERGY all the time.
• Should you buy energy efficient windows?
• Our country needs an energy policy.
• That...
Energy comes in two types:
1. KINETIC ENERGY – the energy of
movement. A moving object, such as the
wind, can do work when...
Velocity v. Mass
Why is the velocity of the object more important than the mass?
Because the velocity is squared.
Quick Quiz
When calculating the kinetic energy of an
object:
• the mass has the greatest effect.
• the velocity has the gr...
2. POTENTIAL ENERGY: is stored energy. An object
does not have to be moving to have energy. There
are two types of potenti...
A) Gravitational: is related to an object’s
mass and height from the ground.
GPE = Mass x Gravity (9.8m/s2
) x Height (mgh)
• The gravitational potential energy of an object
is equal to the work done to lift it.
• Remember that: Work = Force × Di...
Elastic: the energy gained in an object when
it is stretched or compressed.
Elastic Potential Energy
The farther the string
is pulled,
the greater the bow’s
elastic potential energy.
Pulling the str...
Quick Quiz
What happens to an archer’s bow when an
archer pulls back the bow’s string?
• The potential energy of the bow d...
Kinetic and Potential Energy -
Pendulum
Do Now:
1. What happens when you turn on a light
switch?
2. What makes the light bulb emit light?
3. What source of energy...
The 6 forms of energy:
1. Mechanical energy: associated with the
position and motion of objects. It is the
sum of the KE a...
2. Thermal energy
All objects are made up of atoms in motion which
exhibit kinetic energy. The greater the velocity
of the...
3. Electrical energy
This is the energy of flowing electric charge. If
the charges are being stored, that is
potential ene...
4. Chemical energy
This is the type of energy that is stored in the
bonds that hold chemical compounds together.
Last year...
5. Nuclear energy
This type of energy stores potential energy in the
nucleus of the atoms. It is released during a
nuclear...
6. Electromagnetic energy
This type of energy travels by waves.
Electromagnetic energy comes in many forms.
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Energy

  1. 1. Do Now: What does it mean when you say “That person has a lot of energy”?
  2. 2. ENERGY
  3. 3. What have we learned so far? 1. Work is done on an object when a force acts in the direction the object is moving. 2. When work is done on an object, energy is transferred to that object. 3. Simple machines help make doing work easier.
  4. 4. Power is the rate at which work is done. • A tornado and a calm breeze each do the same amount of work if they transfer the same amount of energy to a leaf. • However, the tornado has more power than the breeze because it transfers its energy in less time.
  5. 5. If energy is transferred when work is done, then what is energy? Energy is the ability to do work!
  6. 6. We talk about ENERGY all the time. • Should you buy energy efficient windows? • Our country needs an energy policy. • That little kid at the store who’s screaming at the top of her lungs sure has a lot of energy. • Candy bars are good for an energy boost. • Close the refrigerator; you’re wasting energy!
  7. 7. Energy comes in two types: 1. KINETIC ENERGY – the energy of movement. A moving object, such as the wind, can do work when it strikes another object, a leaf, and moves it some distance. Because the moving object does work, it has energy. KE = 1 x Mass x velocity2 2 Kinetic energy depends on an object’s mass and velocity.
  8. 8. Velocity v. Mass Why is the velocity of the object more important than the mass? Because the velocity is squared.
  9. 9. Quick Quiz When calculating the kinetic energy of an object: • the mass has the greatest effect. • the velocity has the greatest effect. • the mass and the velocity each have an equal effect. • the mass always has half of the velocity’s effect.
  10. 10. 2. POTENTIAL ENERGY: is stored energy. An object does not have to be moving to have energy. There are two types of potential energy. •When you lift a book up to your desk from the floor or compress a spring to wind a toy, you transfer energy to it. •The energy you transfer is stored, or held in readiness. •It might be used later when the book falls to the floor or the spring unwinds.
  11. 11. A) Gravitational: is related to an object’s mass and height from the ground. GPE = Mass x Gravity (9.8m/s2 ) x Height (mgh)
  12. 12. • The gravitational potential energy of an object is equal to the work done to lift it. • Remember that: Work = Force × Distance • The force you use to lift the object is equal to its weight. • The distance you move the object is its height.
  13. 13. Elastic: the energy gained in an object when it is stretched or compressed.
  14. 14. Elastic Potential Energy The farther the string is pulled, the greater the bow’s elastic potential energy. Pulling the string changes the bow’s shape and stores elastic potential energy. The energy stored in a stretched object, such as a bow, is elastic potential energy. •When the energy stored in the bow is released, how is it used?
  15. 15. Quick Quiz What happens to an archer’s bow when an archer pulls back the bow’s string? • The potential energy of the bow decreases. • The potential energy of the bow is unchanged. • The potential energy of the bow increases. • The kinetic energy of the bow increases.
  16. 16. Kinetic and Potential Energy - Pendulum
  17. 17. Do Now: 1. What happens when you turn on a light switch? 2. What makes the light bulb emit light? 3. What source of energy do you use to heat your home?
  18. 18. The 6 forms of energy: 1. Mechanical energy: associated with the position and motion of objects. It is the sum of the KE and PE of the object.
  19. 19. 2. Thermal energy All objects are made up of atoms in motion which exhibit kinetic energy. The greater the velocity of the atoms, the greater the kinetic energy. This atomic velocity results in the production of heat – thermal energy.
  20. 20. 3. Electrical energy This is the energy of flowing electric charge. If the charges are being stored, that is potential energy (a battery has stored energy for future use). If the charges are flowing, that is kinetic energy.
  21. 21. 4. Chemical energy This is the type of energy that is stored in the bonds that hold chemical compounds together. Last year you studied about photosynthesis which produces energy for a plant to survive. The food we eat also produces chemical energy.
  22. 22. 5. Nuclear energy This type of energy stores potential energy in the nucleus of the atoms. It is released during a nuclear reaction. Power plants use nuclear fission, the splitting of atoms, to produce electricity. However, there is a much more destructive use of nuclear power.
  23. 23. 6. Electromagnetic energy This type of energy travels by waves. Electromagnetic energy comes in many forms.

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