energy exponents an exponent tells how many times a number is used as a factor. for example, 3 x 3...
TRANSCRIPT
Energy
Exponents An exponent tells how many times a number is used as a factor. For example, 3 X 3 can be written as 32. You read this number as “three squared.” An exponent of 2 indicates that the number 3 is used as a factor two times. To find the value of a squared number, multiply the number by itself.
32 = 3 X 3 = 9
Practice Problem
What is the value of the number 82?
64
- What Is Energy?
Energy
Energy•The abiltiy to do work
Power•The time rate of doing work
•How fast work is done
Power = Work
Time
Energy - What Is Energy?
Kinetic Energy = ½ mass x velocity2
Kinetic energy increases as mass and velocity increases.
Energy - What Is Energy?
Potential Energy = weight x height
Gravitational potential energy increases as weight and height increase.
Energy
Law of Conservation of Energy
Energy cannot be created or destroyed
Example
Energy
Calculating Mechanical Energy
The kinetic energy of a 500-N diver during a dive from a 10-m platform was measured. These data are shown in the graph.
- Forms of Energy
Energy
Calculating Mechanical Energy
About 1000 J
Reading Graphs:
According to the graph, how much kinetic energy does the diver have at 8 m?
- Forms of Energy
Energy
Calculating Mechanical Energy
Kinetic energy = about 2000 J; potential energy = about 3000 J
Calculating:
Using the graph, find the kinetic energy of the diver at 6 m. Then calculate the diver’s potential energy at that point.
- Forms of Energy
Energy
Calculating Mechanical Energy
About 5000 J
Inferring:
The mechanical energy of the diver is the same at every height. What is the mechanical energy of the diver?
- Forms of Energy
Energy
Forms of Energy
•Thermal Energy•Electrical Energy•Chemical Energy•Nuclear Energy•Electromagnetic Energy
Energy - Energy Transformations and Conservation
Energy Transformations
Most forms of energy can be transformed into other forms.
Energy - Energy Transformations and Conservation
Transformations BetweenPotential and Kinetic Energy
A pendulum continuously transforms energy from kinetic to potential energy and back.
Energy
Energy Transformations Activity
Click the Active Art button to open a browser window and access Active Art about energy transformations.
- Energy Transformations and Conservation
Energy
Question Answer
Asking QuestionsBefore you read, preview the red headings. In a graphic organizer like the one below, ask a question for each heading. As you read, write answers to your questions.
What is an energy transformation?
An energy transformation is a change from one form of energy to another.
What are some examples of transformations between potential and kinetic energy?
Juggling and pendulums show transformations between potential and kinetic energy.
What is conservation of energy?
The law of conservation of energy states that energy cannot be created or destroyed.
- Energy Transformations and Conservation
Energy
End of Section:Energy
Transformations and Conservation
Energy
Formation of Fossil Fuels• See Figure 18 p. 464-5
1.Nuclear energy is transformed to electromagnetic energy
2.Plants and animals transform electromagnetic energy to chemical energy
3.Coal and oil are formed from ancient plants
4.Power plants produce steam to turn turbines
5.Turbines spin to produce electricity
6.Electricity is sinto thermal and mechanical energy
Energy - Energy and Fossil Fuels
Use of Fossil Fuels
Fossil fuels can be burned to release the chemical energy stored millions of years ago.
Energy
Previewing VisualsWhen you preview, you look ahead at the material to be read. Preview Figure 18. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.
Using Fossil Fuel Energy
Q. What energy transformation occurs in the sun?
A. Nuclear energy to thermal energy and electromagnetic energy
Q. What energy transformation takes place when coal is burned?
A. Chemical energy to thermal energy
- Energy and Fossil Fuels
Energy
Links on Energy Transformations
Click the SciLinks button for links on energy transformations.
- Energy and Fossil Fuels
Energy
Use of Fossil Fuels
Click the Video button to watch a movie aboutthe use of fossil fuels.
- Energy and Fossil Fuels
Energy
End of Section:Energy and Fossil Fuels
Energy
exists as measured inis the ability
to do
can bewhich at a
given rate is
Graphic Organizer
Kinetic energy
Energy
Potential energy
Elastic
WorkJoules
Gravitational Power
Energy
End of Section:Graphic Organizer