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Simple Machines: Work, Power, and Efficiency Explained | Video #57

Learn about work, power, and simple machines in this educational video for kids. Discover how to calculate work and power, understand the different types of machines, and explore mechanical advantage and efficiency. Get ready to dive into the fascinating world of physics!

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Simple Machines: Work, Power, and Efficiency Explained | Video #57

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  1. Chapter 15 Work, Power, and Simple Machines Video #57 (simple mach. For kids)

  2. 15-1 Work *force acting through a distance • Work = force X distance • W = F X d • Units: newton-meter(N-m) or Joule(J)

  3. 15-2 Power *how fast work is done -Power = work / time -P = W / t or P = F X d / t

  4. 15-2 Power -Units: N-m / s or J / sec or watt (W) -1J/sec = 1 watt -1000 watts = 1 kilowatt(kW)

  5. -Horsepower *(hp) = to 750 watts (745.56) Video #44 (Science of Golf)

  6. 15-3 Machines *device that makes work easier Video #42 (Real World: W,E,F)

  7. -effort and resistance -make work easier by changing size or dir of applied force *effort force(Fe): force applied to a machine

  8. -effort and resistance *work input(Wi): work done on a machine -Wi = Fe X de Ex: crowbar

  9. -effort and resistance *resistance force(FR): force applied by the machine *Work output(WO): work done by a machine

  10. -effort and resistance *resistance distance(dr): dist through which the object moves -Wo = FR X dR -Machines do not multi work, they can multi force -Worko is never greater than worki

  11. -mechanical advantage *(MA) # of times a machine multi the effort force -MA = FR / FE

  12. -mechanical advantage -MA is not always greater than1, sometimes = to 1,

  13. -mechanical advantage -MA of one changes the dir of the effort force -MA is less than 1, increases the dist an object is moved or the speed with which it is moved

  14. -efficiency *comparison of worko to worki - Efficiency = WO / WI X 100 -High eff = worki is changed to worko -eff can never be greater than 100%

  15. -role of friction -less friction = higher its effic -effic can be increased by reducing friction ex: oil, grease, wax,bearings

  16. 15-4 Simple Machines -6 simp mach: incline plane, the wedge, the screw, the lever, the pulley, and the wheel and axle

  17. -inclined plane *slanted surface used to raise an object(a ramp) -smaller effort force, but moved through a greater distance

  18. -inclined plane -MA = length of the plane divided by its height -length can never be shorter than its height -MA = never be < 1

  19. -wedge and screws *wedge: incline plane that moves -large force exerted on a small surface

  20. -wedge and screws -longer and thinner the less effort force required ex: sharpening

  21. -wedge and screws *screw: an incline plane wrapped around a cylinder to form a spiral -multi an effort force by acting through a long effort distance -the closer the threads > the MA

  22. -levers *bar that is free to pivot about a fixed point when effort force is applied ex: seesaw, shovel, nutcracker, crowbar *fulcrum: is the fixed point

  23. -levers -3 classes of levers -based on the position of the fulcrum, effort force, resist force

  24. -levers • 1st class: multi effort force and also change dir Ex: pliers, scissors, seesaws

  25. -levers 2) 2nd class: resist force is between the fulcr and the effort force -multi eff force but does not change dir Ex: wheelbarrow, door, nutcracker

  26. -levers 3) 3rd class: eff force > resistan -doesn’t multi force -multi dist of eff force

  27. -levers -MA: # of times the lever increases the eff force *effort arm: dist from the eff force to the fulc *resist arm: dist from resis force to the fulc

  28. -levers -MA = eff arm length resist arm length -1st and 2nd levers mult the eff force -3rd levers multi the distance

  29. -pulleysvideo #43 (pulley simple machines) -can change either dir or amount of eff force -fixed pulley: attached to a stationary object -can’t multi eff force -change dir of eff force

  30. -pulleys -MA of a fixed pulley is 1

  31. -pulleys -movable pulley: -can multi eff force -can’t change dir of an eff force -MA>1

  32. -pulleys -can predict MA by counting the number of supporting sections of rope.

  33. Complex Machines *is a combination of 2 or more simple machines. **you can get no more work out of a machine than you put in it! Video: 49 (pumkin chuckin)

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