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Conservation of energy

Conservation of energy. Roller Coaster Energy. Kingda Ka. 440 ft tall. Energy and a Roller Coaster. Does the Car possess the same type of energy throughout its run?. Where does the car have the most KE? Where does the car have the most GPE? How are the cars stopped?. Types of energy.

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Conservation of energy

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  1. Conservation of energy

  2. Roller Coaster Energy

  3. Kingda Ka • 440 ft tall

  4. Energy and a Roller Coaster

  5. Does the Car possess the same type of energy throughout its run?

  6. Where does the car have the most KE? Where does the car have the most GPE? How are the cars stopped? Types of energy

  7. Is energy added to the car throughout the run? Where? How? Is energy taken away from the roller coaster? How?

  8. Roller Coaster Questions • Where should the tallest hill be on a roller coaster? • How are most roller coasters stopped? • Are most coasters stopped instantly? • Kingda Ka is about 120 meters high. What would your GPE be at the top. Assuming no air loss what would be your KE at the bottom?

  9. Energies connected to our track • Mechanical • KE • GPE • EPE • Non-mechanical • Sound • Thermal

  10. Roller coaster

  11. Energy of a roller coaster • Kinetic Energy of the chain transfers to KE of the coaster GPE of coaster other forms of energy

  12. Name all the Energy transfers/transformation in a chain-driven roller coaster ride Name all objects involved in moving of energy

  13. Definition of C of E

  14. Conservation of Energy • Like momentum, energy can be transferred from one object to another • Unlike momentum, energy can also be transformed from one type to another

  15. Conservation of energy • For an isolated or closed system (hard to do in real life) Energy is not created or destroyed, only transferred or transformed

  16. Example problem • A 50 kg man dives off a 20 m high cliff. Assuming his initial velocity was zero and no air resistance: • Determine the initial amount of GPE the man has • Determine how much KE he has halfway through the dive • Determine the velocity at which he is falling halfway through the dive.

  17. Conservation of Energy • Given a closed system: • Energy can not be created or destroyed, only transferred or transformed • Examples

  18. Conservation of energy • Closed system – energy remains constant in system over time • Open system – energy flows in/out of the system • Law– in a closed system, energy can not be created or destroyed, only transferred/transformed.

  19. Change in Energy • Energy Transformations: Energy is utilized in everyday life through by being transferred or transformed. Transferred means energy is passed from one object to the next Transformed means energy is changed from one type to at least one other type

  20. Conservation • Does not mean that we are Not trying to waste energy or reduce the amount we use • Means that for a closed system the amount of energy in the system is constant at all times

  21. Formal definition of Conservation of energy • For a closed system: • Energy can not be created or destroyed, only transferred or transformed.

  22. Transferring and Transforming Energy

  23. Transfer of Kinetic energy • Switching a light switch on or off • Bumping into someone • Kicking a ball Can you think of 3 more transfers of Kinetic energy between 2 objects since you woke up?

  24. Transfer of kinetic to potential • Load an object up with more energy than what it had at the start. • Lifting a book off the desk • Stretching a rubberband Can you think of 3 more examples of loading an object with more potential energy you witnessed this morning?

  25. Transfer is not always a one to one experience • Energy may be transferred to more than one object or energy type at any instant in time

  26. Transforming energy • Change from one type of energy to different energy types • On roller coaster change to thermal energy sound energy

  27. Transferring or transforming energy is not usually a one for oneexperience

  28. Examples of Transforming energy • Anything involving friction • Batteries • Can you think of at least 3 transformation of energy involved in your life over the last week?

  29. Energy transfer/transformations explain the flight of the ball

  30. Energy transformations/transfers explain the bouncing of a ball

  31. Ease of creating a closed system for energy • Much harder to produce a closed system for energy than momentum

  32. Other Examples of Conservation of Energy

  33. Basketball drop Observe the action of the basketball being dropped. List the types of energy changes that occur between the basketball, the ground and the surrounding air through the entire event Does the ball have the same amount of energy at the end as it had at the moment of release?

  34. How about when a ball drops? • Is energy taken away? • What type of energy is gained as the ball drops, and what type of energy is lost?

  35. Ball • As ball drops, GPE is transformed into KE • A tiny amount is lost to air resistance, sound

  36. What type of mechanical energy does he have before he dives off the cliff? At the midway point of the dive As he enters the water Cliff diver

  37. Spring launch

  38. When is energy of the rollercoaster transformed during the ride? When is it Transferred to some other thing, during the ride?

  39. Example problem • A 50 kg man dives off a 20 m high cliff. Assuming his initial velocity was zero and no air resistance: • Determine the initial amount of GPE the man has • Determine how much KE he has halfway through the dive • Determine the velocity at which he is falling halfway through the dive.

  40. Remember • An object tends to have several types of energy • Energy of one type may be transformed into energy of more than a single type • Example, a roller coaster car moving down on a piece of track

  41. Systems

  42. What is a system? What makes a system open or closed

  43. Scientists study energy systems • Look to identify energy cycles (systems) at work in our lives • Open Systems, Closed Systems

  44. What is a system? What makes a system open or closed

  45. System • A group of objects which interact with each other (Could include the surrounding environment) • All the components in your body • This school • Transportation to get to school

  46. Systems • A system is composed of 1 or more objects that have a connection to each other • CLOSED system = No energy is lost • OPEN system = Energy is lostgained in relationship to the non-included environment

  47. Systems ?

  48. If system is closed • Total energy is constant at every point in time • If you know the total amount at any point of time, you know it for all times

  49. Closed Systems?

  50. Closed system in energy • A system will be considered closed if there is no significant energy gained or lost from outside the parts of the system • No big outside source of energy • No significant air resistance or friction

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