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Simple Machines

Learn about the different types of simple machines, how they make work easier, and how to calculate work, mechanical advantage, and efficiency. Explore levers, pulleys, inclined planes, and the wheel and axle.

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Simple Machines

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  1. Simple Machines 1 Sound Efficiency Effort Mechanical Advantage WORK Force

  2. 2 What do I need to know? Goals 1.Analyze the simple machines qualitatively and quantitatively in terms of force, distance, work and mechanical advantage 2. Explain the different types of simple machines. 3. Be able to calculate amount of work done by a simple machine 4.Be able to calculate mechanical advantage 5. Use mathematics & computational thinking to identify the relationships between work, mechanical advantage, and 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. 7.1 Mechanical Advantage CLIP Number of times the machine multiplies the effort force (The force you apply to it)

  8. 7.1 Ideal vs Actual Mechanical Advantage IMA IMA WHAT ACTUALLY happened!! Why is this different from IMA?

  9. 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.

  10. Working Together

  11. 9 Efficiency of a Machine A measure (%) of how much work put into a machine is actually changed to useful work put outby the machine. 90 J . 100 J NEVER OVER 100%

  12. 10 Ideal machine Efficiency =100% According To “The Law of Conservation of Energy” Can this exist? Does not exist. FRICTION

  13. 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?

  14. 12 Levers Fulcrum Resistance Distance Effort Distance LOAD Effort Arm Resistance Arm Resistance Force Effort Force

  15. 13 Levers There are three types of Levers Based on the position of the fulcrum

  16. 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.

  17. 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

  18. 16 3rd Class: the effort force is between the resistance force and the fulcrum. Levers • Garden Hoe • Your arm • Catapult • Fishing rod • Tongs(double lever) (where hinged at one end)

  19. 17 Mechanical Advantage of Levers 3 Ways 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.

  20. Mechanical Advantage of Levers You can also use the Mechanical Advantage Formulas: IMA Ideal MA AMA Actual MA

  21. 18 REVIEW Position of Fulcrum

  22. MA of Levers Problems • To pull apart two pieces of wood, you apply a force of 50 N to a lever. The lever then applies a force of 640 N to the wood. What is the mechanical advantage of the lever? • A lever and fulcrum are used to raise a heavy rock, which has a weight of 350 N. If the lever has a mechanical advantage of 9, what must the input force on the lever be in order to just begin lifting the rock? • A construction worker uses a board and log as a lever to lift a heavy rock. If the input arm is 6 meters long and the output arm is 1.2 meters long, what is the mechanical advantage of the lever?

  23. TedEd: The mighty mathematics of the lever What does he say at 1:20 that is wrong?

  24. 19 Pulleys

  25. 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

  26. 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

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

  28. Mechanical Advantage of Pulleys 23 MA =2

  29. Mechanical Advantage of Pulleys 24 MA =2

  30. Mechanical Advantage of Pulleys 25 MA =4

  31. 26

  32. 27

  33. 28 Inclined Plane A sloping surface that that reduces the amount of force required to raise and object. Resistance Distance (h) Effort Distance (l)

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

  35. Mechanical Advantage of Inclined Planes 30

  36. Animation Starter on page 6 in packet…click

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

  38. 31.b Ideal Mechanical Advantage = Radius of wheel Of wheel and axle        Radius of axle The effort force is applied to the larger wheel Gears are wheels with teeth.

  39. 31.c • One day you made a mousetrap cars. The car has the following measurements for their wheels:  the radius axle (the small wheel) measured only 1 cm.  The radius of the larger wheel (the one that touched the pavement) measured a whopping 10cm.  What was the mechanical advantage of these wheels? Ideal Mechanical Advantage = Radius of wheel Of wheel and axel        Radius of axel This means with each turn of the axle, you get 10 times the distance.  Those big wheels really help!

  40. 32 Screw • An inclined plane wrapped around a cylinder • The inclined plane lets the screw slide into the wood. Examples: Bolt, Spiral Staircase

  41. 33

  42. 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

  43. Review Clip 35

  44. 36 Rube Goldburg Keep You From Forgetting To Mail Your Wife's Letter

  45. 37 Simplified Pencil Sharpener CLIP

  46. EOCT QUESTIONS 38

  47. 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

  48. 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

  49. 41 Which of the following is an example of a compound machine? A bicycle B crowbar C doorknob D ramp

  50. Simple Machines: Pulleys (12:52)

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