4.2 The Unit Circle! Whoa wait a sec, where does all that stuff come from?
Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical...
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Transcript of Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical...
![Page 1: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/1.jpg)
Chapter 4:
EnergySec 4.1: The Nature of Energy
Sec 4.2: Conservation of Energy
9th Grade Physical Science
![Page 2: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/2.jpg)
What is energy? 4.14.1
The Nature of EnergyThe Nature of Energy
Energy is the ability to cause change.
There are many different forms of energy including: light, sound, heat, chemical, nuclear, electrical, potential, and kinetic energy
![Page 3: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/3.jpg)
ENERGY OF MOTION!• Energy that appears in the form of motion is
called kinetic energy.
• The amount of kinetic energy a moving object has depends on the mass of the object and its velocity.
• The unit of energy is the joule(pronounced jewel), named after James Prescott Joule, an English scientist.
KE = ½ mv2
![Page 4: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/4.jpg)
Potential Energy 4.14.1The Nature of EnergyThe Nature of Energy
• A hanging apple in a tree has stored energy.
• Even motionless objects can have energy. Energy is stored in the object.
![Page 5: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/5.jpg)
Gravitational Potential Energy4.14.1The Nature of EnergyThe Nature of Energy
• On Earth the acceleration of gravity is 9.8 m/s2, and has the symbol g.
• Gravitational potential energy (GPE) is energy stored by objects due to their position above Earth’s surface.
![Page 6: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/6.jpg)
• If you stretch a rubber band and let it go, it sails across the room.
Elastic Potential Energy 4.14.1The Nature of EnergyThe Nature of Energy
• As it flies through the air, it has kinetic energy due to its motion.
• Elastic potential energy is energy stored by something that can stretch or compress, such as a rubber band or spring.
![Page 7: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/7.jpg)
4.24.2Mechanical energy is the total amount of
potential and kinetic energy in a system.
mechanical energy = potential energy + kinetic energy
![Page 8: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/8.jpg)
• Energy can change from one form to another, but the total amount of energy never changes.
The Law of Conservation of Energy
4.24.2Conservation of Energy Conservation of Energy
• The law of conservation of energy states that energy cannot be created or destroyed. The total amount of energy in the
universe is constant.
![Page 9: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/9.jpg)
Potential Energy
Mechanical Energy is not lost
Kinetic Energy
Potential Energy & Kinetic
Energy are
both forms of Mechanical
Energy
![Page 10: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/10.jpg)
• The mechanical energy of the ball remains constant from the time it’s hit until it lands.
Energy Transformations in Projectile Motion
4.24.2Conservation of Energy Conservation of Energy
![Page 11: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/11.jpg)
4.14.1Section CheckSection Check
Question 1
A.) change B.) heatC.) motionD.) work
Energy is the ability to cause __________.
A!Energy causes
change.
![Page 12: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/12.jpg)
4.14.1Section CheckSection Check
Question 2
What are the two types of energy we’re studying?
We’re studying: kinetic and
potential(elastic, chemical, gravitational)
Answer
kp
![Page 13: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/13.jpg)
4.14.1Section CheckSection Check
Question 3
A.) the object’s speedB.) the object’s massC.) the object’s mass and speedD.) the acceleration of the object
The kinetic energy of an object depends on __________.
KE = ½ mv2
![Page 14: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/14.jpg)
![Page 15: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/15.jpg)
• You might have heard about energy conservation or been asked to conserve energy.
Conserving Resources 4.24.2
Conservation of Energy Conservation of Energy
• These ideas are related to reducing the demand for electricity and gasoline, which lowers the consumption of energy resources such as coal and fuel oil.
![Page 16: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/16.jpg)
• While coasting along a flat road on a bicycle, you know that you will eventually stop if you don’t pedal.
Is energy always conserved? 4.24.2
Conservation of Energy Conservation of Energy
• If energy is conserved, why wouldn’t your kinetic energy stay constant so that you would coast forever?
![Page 17: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/17.jpg)
The Effect of Friction 4.24.2
Conservation of Energy Conservation of Energy
• You know from experience that if you don’t continue to pump a swing or be pushed by somebody else, your arcs will become lower and you eventually will stop swinging.
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The Effect of Friction
4.24.2
Friction and air resistance cause some of the mechanical energy of the swing to change to thermal energy.
![Page 19: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/19.jpg)
Converting Mass into Energy 4.24.2
Conservation of Energy Conservation of Energy
During this process a small amount of mass is transformed into a tremendous amount of energy. (more than fission)
The Sun (and other stars) run by nuclear fusion.
We do not currently have the technology to create energy with fusion.
![Page 20: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/20.jpg)
Nuclear Fission 4.24.2
Conservation of Energy Conservation of Energy
Nuclear fission produces huge amounts of energy while splitting atoms apart.
This is the technology used in atomic bombs.
![Page 21: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/21.jpg)
• What forms of energy can you find in the human body?
The Human BodyBalancing the Energy Equation
4.24.2Conservation of Energy Conservation of Energy
• With your right hand, reach up and feel your left shoulder.
• With that simple action, stored potential energy within your body was converted to the kinetic energy of your moving arm.
![Page 22: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/22.jpg)
• Much of the chemical potential energy stored in your body is used to maintain a nearly constant internal temperature.
The Human BodyBalancing the Energy Equation
4.24.2Conservation of Energy Conservation of Energy
• A portion of this energy also is converted to the excess heat that your body gives off to its surroundings.
![Page 23: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/23.jpg)
• Your body stores energy in the form of fat and other chemical compounds.
Energy Conversions in Your Body 4.24.2
Conservation of Energy Conservation of Energy
• This chemical potential energy is used to fuel the processes that keep you alive, such as making your heart beat and digesting the food you eat.
![Page 24: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/24.jpg)
• The food Calorie (C) is a unit used to measure how much energy you get from various foods1 C is equivalent to about 4,184 J.
Food Energy 4.24.2
Conservation of Energy Conservation of Energy
• Every gram of fat a person consumes can supply 9 C of energy.
• Carbohydrates and proteins each supply about 4 C of energy per gram.
![Page 25: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/25.jpg)
4.24.2Section CheckSection Check
Question 1
A.) potential and kinetic B.) momentumC.) potential energyD.) kinetic energy
Mechanical energy is the total amount of _________ in a system.
mechanical energy =
KE + GPE
![Page 26: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/26.jpg)
4.24.2Section CheckSection Check
Question 2
State the law of conservation of energy.
The law of conservation of energy states that energy cannot be created or destroyed.
Answer
![Page 27: Chapter 4: Energy Sec 4.1: The Nature of Energy Sec 4.2: Conservation of Energy 9 th Grade Physical Science.](https://reader037.fdocuments.net/reader037/viewer/2022103101/56649e7a5503460f94b7aa56/html5/thumbnails/27.jpg)
4.24.2Section CheckSection Check
Question 3
A.) electrical, thermalB.) mechanical, thermalC.) thermal, electricalD.) thermal, mechanical
Friction converts __________ energy into ___________ energy.
mechanical
thermal