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Conservation of Energy Where does energy come from?

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Conservation of Energy Where does energy come from? Changing Forms of Energy Energy is most noticeable as it transforms from one type to another. – PowerPoint PPT presentation

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Title: Conservation of Energy Where does energy come from?


1
Conservation of EnergyWhere does energy come
from?
2
Changing Forms of Energy
  • Energy is most noticeable as it transforms from
    one type to another.
  • What are some examples of transforming electrical
    energy?
  • A lightbulb
  • A hair dryer

3
Changing forms of Energy
  • An example of transforming chemical energy is a
    car engine. Chemical potential energy in
    gasoline is transformed into kinetic energy of
    the car as it moves!!

4
KE and PE
  • In many situations, there is a conversion between
    potential and kinetic energy.
  • The total amount of potential and kinetic energy
    in a system is called the mechanical energy
  • Mechanical energy PE KE

5
Mechanical Energy
  • Mechanical energy is due to the position and
    motion of the object.
  • What happens to the mechanical energy of an apple
    as it falls from a tree?

6
Mechanical Energy
  • As the apple falls to the ground, its height
    decreases. Therefore, its GPE decreases.
  • The potential energy is not lost it is converted
    into kinetic energy as the velocity of the apple
    increases.
  • What happens to the mechanical energy?

7
Mechanical Energy
  • The mechanical energy does not change because the
    loss in potential energy is simply transferred
    into kinetic energy.
  • The energy in the system remains constant!!

The total amount of energy stays the SAME!!
8
Swinging Along
  • Think about the changes in energy when you are on
    a swing
  • At what point do you have the most potential
    energy?
  • At what point do you have the most kinetic
    energy?
  • What happens to the mechanical energy?

9
The Law of Conservation of Energy
  • The Law of Conservation of Energy states that
    energy cannot be created or destroyed.
  • The big picture the total energy in the universe
    remains constant.

10
  • But how? If I stop pumping while Im swinging, I
    stop!! So, wheres the energy?
  • Bill Nye -- Energy

11
Conservation of Energy
  • You need to remember friction
  • As you slow down on the swing, the hooks and the
    chain rub against each other and air pushes
    against the rider.

12
  • Friction causes some of the mechanical energy of
    the swing to change to thermal energy and the
    temperature of the hooks and chain heat up a
    little.
  • The energy is still there, just in a different
    form!!
  • Bill Nye -- Friction

13
Conservation of Energy
  • Energy is transformed not destroyed!!

The total amount of energy stays the SAME!!
14
Energy in Your Body
  • Even the energy converted in your body follows
    the law of conservation of energy.
  • Chemical potential energy is transferred to
    kinetic energy that allows your body to move!!

15
Calories
  • A Calorie (C) is a unit to measure energy in
    foods.
  • 1 Calorie is equal to about 4,184 Joules.
  • A person uses about
  • 55 Calories while sleeping for 1 hour
  • 210 Calories while walking for 1 hour
  • 850 Calories while running for 1 hour

16
Is Perpetual Motion Possible?
  • Read p. 256
  • Why is perpetual motion not possible?
  • Because energy conversions always result in the
    production of waste thermal energy.

17
Non-renewable resources
  • Read p. 258
  • Define a non-renewable resource.
  • A resource that forms at a rate that is much
    slower than the rate at which it is consumed.
  • What is a fossil fuel?
  • Energy resources made from the buried remains of
    plants and animals that lived millions of years
    ago.

18
Nuclear Energy
  • Read p. 260
  • What is nuclear energy?
  • Thermal energy that is obtained by splitting the
    atoms of radioactive materials.

19
Renewable resources
  • Read p.261-262
  • List the 5 types of renewable resources
  • Solar
  • Energy from water
  • Wind
  • Geothermal
  • Biomass

20
Renewable resources
  • Describe solar energy
  • Changing sunlight into electrical energy through
    solar cells
  • Describe Energy from Water
  • Dams block water, then lets it flow over turbines
    to make energy.
  • Hydroelectricity

21
Renewable resources
  • Describe wind energy.
  • Wind turns wind turbines that change the kinetic
    energy of air into electrical energy us turning a
    generator
  • Describe Geothermal energy
  • Water is pumped underground to hot rocks that
    produces stream that turns the turbines of a
    generator.

22
Renewable Resources
  • Describe Biomass
  • Burning plants, wood, and waste to create energy.
  • What is fire?
  • Coal Power Plant

23
Copy these to your notebook
  • Table 1 p. 262
  • Figure 3 p. 260
  • Figure 2 p. 259
  • Figure 1 p. 254
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