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8th grade PE and KE introDUCTION FOR STUDENTS
- 2. Table of Contents •How is work, power and energy related? • What is energy? – 2 types • Kinetic • Potential – 2 types » Gravitational » Elastic
- 3. Table of Contents •What are other forms of energy? 1. Mechanical 2. Thermal 3. Electrical 4. Chemical 5. Nuclear 6. Electromagnetic
- 4. Work, Power andEnergy • What is WORK? – Work is done on an object when the object moves in the same direction that the force was applied. • Lifting your book bag • Work= Force (N) x Distance (m) – 1Nm = 1J • What is POWER? – The rate at which work is done. • Running vs walking with your book bag • Power= work (J) / time (s) – 1J/s = 1W
- 5. Work, Power, Energy •Energy: The ability to do work or cause a change. – Whenever work is done energy is transferred to that object. – Power is the rate at which the energy is transferred. • What do YOU think the unit for energy is? JOULES YAY!
- 6. Two Types ofEnergy 1. Kinetic Energy 2. Potential Energy
- 7. Kinetic Energy • “Themoving energy”
- 8. Kinetic Energy • KineticEnergy increases as mass and velocity increase
- 9.
- 10. Kinetic Energy • Velocityis squared – Would velocity have the same, less or more of a effect than mass on the kinetic energy of an object? MORE
- 11. Kinetic Energy Example •1. Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s. • 2. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy?
- 12. • An objectcan have energy even when its not moving! – Stored energy based off of the objects shape or position
- 13. Potential Energy • Energyis stored or held in readiness – Book on your desk – Apple hanging from a tree – Pulling back a rubber band • If the apple stays in the tree, it will keep the stored energy due to its height above the ground. • If the apple falls, that stored energy of position is converted to energy of motion.
- 14. Types of PotentialEnergy 1. Gravitational Potential Energy (GPE) 2. Elastic Potential Energy
- 15. Gravitational Potential Energy(GPE) • GPE: The potential energy related to an objects position above earths surface. – Lifting your book on top of your desk = the work you did to lift it • Distance the book was moved: height • Force you used to lift it: weight
- 16. Gravitational Potential Energy(GPE) • Gravitational Potential Energy increases as weight and height increase.
- 17. Gravitational Potential Energy(GPE) • To calculate GPE use this equation. • On Earth the acceleration of gravity is 9.8 m/s2 and has the symbol g (in this equation)
- 18. Changing Gravitational Potential Energy(GPE) • The Gravitational potential energy of an object can be increased by increasing the height. • If the objects are at the same height then what? – The object with the larger mass would have more gravitational pull.
- 19. Elastic Potential Energy •Elastic Potential Energy: potential energy associated with objects that can be stretched or compressed. – Pulling back a rubber band – Winding up a toy
- 20. Elastic Potential Energy •The rubber band has elastic potential energy here because it has been stretched and is storing its energy. • If you let the rubber band go, it sails across the room. – As it flies through the air it has kinetic energy due to its motion.
- 21. Remember this! • Energycomes in MANY different forms!!!!
- 22. Mechanical Energy • Whatis Mechanical Energy? – – Motion Mechanical = Potential + Kinetic
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- 25. • If thekinetic energy of a falling apple is 5.2J and its mechanical energy is 8.7J what is its potential energy?
- 26. Potential = Kinetic Kinetic= Potential Mechanical Energy • To sum up… – An object with mechanical energy can do work on another object! – The more mechanical energy an object has the more work it can do! Law of Conservation of Energy Energy can neither be created nor destroyed; rather, it transforms from one form to another.
- 27. Thermal Energy • Allobjects are made up of particles called _____ and _________. • These particles are always in motion. – What kind of energy would they have? Kinetic • These particles are arranged in specific ways in different objects – What kind of energy would they have? Potential atoms molecules
- 28. Thermal Energy • Totalpotential and kinetic energy of the PARTICLES in a object is called Thermal Energy!
- 29. Electrical Energy • Whatdo you think this is? – Again this is energy of particles! – The energy of tiny charged particles called….. – Lets think of some examples.... ELECTRONS!!!!
- 30. Chemical Energy • Chemicalcompounds are made up of _____ and _________. • Bonds hold these atoms and molecules together. • These bonds have Chemical Energy!!!! • Chemical energy can be released when these bonds break!!! atoms molecules
- 31. Chemical Energy • ChemicalPotential Energy: energy that is stored in chemical bonds • Energy is stored in the bonds that hold carbon and hydrogen atoms together – The atoms are released when gas is burned
- 32. Nuclear Energy • Potentialor Kinetic? • Where is the energy stored? – NUCLEUS! • When is the energy released? – NUCLEAR REACTIONS! • 2 kinds 1. Nuclear Fission • Example? 2. Nuclear Fusion • Example?
- 35. Electromagnetic Energy • Travelsin waves – Does anyone know what waves are? – These waves have… • Electrical properties • Magnetic properties • What are some examples that we know of that use waves to transfer energy? Electromagnetic!
- 36.