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Simple Machines

Simple Machines. 1. Effort. Efficiency. Mechanical Advantage. WORK. Force. 2. Goals. Analyze the simple machines qualit atively and quant itatively in terms of force, distance, work and mechanical advantage. Be able to calculate mechanical advantage.

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Simple Machines

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  1. Simple Machines 1 Effort Efficiency Mechanical Advantage WORK Force

  2. 2 Goals • Analyze the simple machines qualitatively and quantitatively in terms of force, distance, work and mechanical advantage • Be able to calculate mechanical advantage • Be able to calculate amount of work done by a simple machine • Explain the different types of simple machines.

  3. 3 Work FLASH BACK • Transfer of Energy from one place to another. • Applying a force over a certain distance. • Calculating Work: • Work= Force x distance • W = f x d

  4. 4 6types of simple machines clip

  5. 5 What is a machine? A device that makes work easier. What is a simple machine? -a machine that does work with only one movement. You still do the same amt of work —it’s just easier!

  6. 6 A machine can make work easier in two ways: • Multiply the force you apply. • A Car Jack • Change the direction of the force. • Blinds

  7. Mechanical Advantage 7 CLIP Number of times the machine multiplies the effort force(The force you apply to it)

  8. 8 Watch for this in all Simple machines: Machines are a “give and take relationship.” If you get your force multiplied, then you must go a greater distance.

  9. 9 Efficiency of a Machine A measure (%) of how much work put into a machine is actually changed to useful work put out by the machine. 90 J . 100 J NEVER OVER 100%

  10. 10 Ideal machine Efficiency =100% MA= 100% According To “The Law of Conservation of Energy” Can this exist? Does not exist. FRICTION

  11. 11 Types of MachinesLevers A lever is a bar that is free to pivot, or turn about a fixed point. How can we use levers?

  12. 12 Levers Fulcrum Resistance Distance Effort Distance LOAD Effort Arm Resistance Arm Resistance Force Effort Force

  13. 13 Levers There are three types of Levers Based on the position of the fulcrum

  14. 14 Levers 1st Class: Crowbars, pliers, scissors, seesaw The fulcrum is between the resistance force and the effort force. The closer the fulcrum to the resistance force, the more the lever multiplies the force.

  15. 15 Levers 2nd Class: The resistance force is between the effort force and the fulcrum. • Wheelbarrow • Nutcrackers • Crowbar (forcing two objects apart) • The handle of a pair of nail clippers

  16. 16 3rd Class: the effort force is between the resistance force and the fulcrum. Levers • Hoe • Your arm • Catapult • Fishing rod • Tongs (double lever) (where hinged at one end)

  17. Mechanical Advantage of Levers 17 5/5=1 10/5=2 20/5=4 Effort arm Resistance arm As the length of the effort arm increases, the MA of the lever increases.

  18. 18 REVIEW Position of Fulcrum

  19. 19 Pulleys

  20. 20 Pulleys • What is a pulley? • A pulley is a grooved wheel with a rope or chain running along the groove. • What can a pulley be used for? • Multiply the effort force • change the direction of the force

  21. 21 Pulleys Two types of Pulleys: • Fixed pulley • A pulley that is attached to something • Only changes the direction of the force • Movable pulley • The pulley is free to move ***Block and Tackle*** Combination of both types of pulleys

  22. Mechanical Advantage of Pulleys 22 • Only changes the direction of the force MA =1 10 N resistance Force Effort Force 10 N

  23. Mechanical Advantage of Pulleys 23 MA =2

  24. Mechanical Advantage of Pulleys 24 MA =2

  25. Mechanical Advantage of Pulleys 25 MA =4

  26. 26

  27. 27

  28. 28 Inclined Plane A sloping surface that that reduces the amount of force required to raise and object. Resistance Distance (h) Effort Distance (l)

  29. Mechanical Advantage of Inclined Planes 29 Effort Distance (l) Resistance Distance (h)

  30. Mechanical Advantage of Inclined Planes 30

  31. 31 Wheel and Axle • Consisting of two wheels of different sizes that rotate together • The effort force is applied to the larger wheel

  32. Ideal Mechanical Advantage = Radius of wheel     Of wheel and axel         Radius of axel Gears are wheels with teeth.

  33. 32 Screw • An inclined plane wrapped around a cylinder • The inclined plane lets the screw slide into the wood. Examples: Bolt, Spiral Staircase

  34. 33

  35. 34 Wedge • An inclined plane with one or two sloping sides. • Changes the direction of the effort force. Examples: Axe, Zipper, Knife Effort Force Resistance force

  36. Review Clip 35

  37. 36 Rube Goldburg

  38. 37 CLIP

  39. EOCT QUESTIONS 38

  40. A lever is used to lift a box. The mechanical advantage of the lever is 39 It took only 200 N of force to lift a 1000N object, therefore the machine multiplied the force 5 times! OR 50 cm 10 cm A25 B10 C5 D4

  41. 40 What is the amount of useful work output of a 25% efficient bicycle if the amount ofwork input is 88 N-m? A 2200 N-m B 113 N-m C 63 N-m D 22 N-m Wout .25 = 88 J

  42. 41 Which of the following is an example of a compound machine? A bicycle B crowbar C doorknob D ramp

  43. Simple Machines

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