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Work and Energy

Work and Energy. ENERGY. The ability to do work. WORK. A change in energy. Work. Energy. Circular Definition!. Forms of Energy. Chemical. Sound. Radiant. Electrical. Mechanical. Magnetic. Thermal. Nuclear. Radiant Energy. Chemical Energy. Electrical Energy.

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Work and Energy

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  1. Work and Energy

  2. ENERGY The ability to do work

  3. WORK A change in energy

  4. Work Energy

  5. Circular Definition!

  6. Forms of Energy Chemical Sound Radiant Electrical Mechanical Magnetic Thermal Nuclear

  7. Radiant Energy

  8. Chemical Energy

  9. Electrical Energy At home – check out http://www.youtube.com/watch?v=3ff_AXVlo9U for the Singing Tesla Coil!

  10. Nuclear Energy

  11. Thermal Energy

  12. Sound Energy

  13. Magnetic Energy

  14. Mechanical Energy Potential energy + Kinetic energy = Mechanical energy

  15. Mechanical Energy Potential energy + Kinetic energy = Mechanical energy Example of energy changes in a swing or pendulum.

  16. 2 Kinds of Mechanical Energy • Kinetic energy (KE) • Potential Energy (PE) • Gravitational PE (PEg) • Elastic PE (PEelastic)

  17. Kinetic Energy Energy due to motion KE = ½ mv2

  18. Potential Energy Energy due to position

  19. Bowling Ball – Conservation of Energy

  20. Conserving Energy

  21. Gravitational PE PEg = mgh

  22. A 25 kg boy runs with a speed of 6.5 m/s. How much kinetic energy does the boy have? 530 Joules

  23. How much potential energy does a 0.50 kg apple have if it hangs from a tree 13m above the ground? 64 Joules

  24. A 220 gram fly has a kinetic energy of 55 Joules. How fast is the fly flying? 22 m/s

  25. ENERGY IS CONSERVED!!

  26. WORKW = FDs(Work = Force x displacement) Units: Joule (J) = N· m

  27. Work is done only when components of a force are parallelto a displacement.

  28. A student drags his book bag 15 meters across the classroom by pulling on it with a force of 5.0 Newtons. How much work does the student do on the bag? 75 Joules

  29. Larry carries his 35N physics book across the room 25m away. How much work does he do on the book? 0 Joules

  30. Work-Kinetic Energy Theorem Wnet = DKE

  31. POWER The rate at which work is done

  32. W Dt P= Or…

  33. DKE Dt P= Or…

  34. DPE Dt P= Or…

  35. P = Fv= Force * velocity

  36. The SI unit of power is the Watt, named in honor of James Watt. One Watt, W, of power is the power achieved when 1.0 J of work is done or 1.0 J of energy is transferred in a time of 1.0 s.

  37. Unit of Power Watt = 1 J/s Horsepower (hp) = 746 W

  38. How much power is generated by a motor that can lift a 5300 kg crate of bricks with a velocity of 15 m/s? 780,000 W

  39. How much power is generated by a car engine that does 5500 Joules of work in 35 seconds? 160 W

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