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Do Now 3 /3/2014

Do Now 3 /3/2014. Take 4 sheets from back table Homework – Simple Machine worksheet Test Thursday. Simple Machines. Levers. A lever is a rigid bar that is free to pivot, or rotate, about a fixed point. The fixed point that a lever pivots around is called the fulcrum . .

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Do Now 3 /3/2014

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  1. Do Now 3/3/2014 • Take 4 sheets from back table • Homework – Simple Machine worksheet • Test Thursday

  2. Simple Machines

  3. Levers • A lever is a rigid bar that is free to pivot, or rotate, about a fixed point. • The fixed point that a lever pivots around is called the fulcrum.

  4. Ideal Mechanical Advantage of a lever • I.M.A= Distance from fulcrum to input force Distance from fulcrum to output force

  5. Input force Output force First Class Lever

  6. FIRST CLASS LEVERS • The Fulcrum (fixed pivot point) is located between the Input and the Output Forces.  A SEESAW. • The Input and the Output Forces move in opposite directions.  The Input Down in order to Lift the Load. • When the Fulcrum is closer to the Input than to the Output, there is a Loss in Force but a Gain in Speed and Distance.

  7. FIRST CLASS LEVERS • When the Fulcrum is closer to the Output than to the Input, there is a Loss in Speed and Distance, but a Gain in Force. • When the fulcrum is Midway between the Input and the Output, there is no change in Force, Speed or Distance. • Samples of First Class Levers – Seesaw, Crowbars, Scissors, and Claw Hammers.

  8. Output force Input force Second Class Lever

  9. SECOND CLASS LEVERS • The Output Force is between the Input Force and the Fulcrum. • The Fulcrum is at one End of the Lever. • The Fulcrum is usually closer to the Output Force, (load).

  10. SECOND CLASS LEVERS • Second Class Levers produce a gain in Force. • Samples of Second Class Levers – Wheelbarrow, Bottle Openers, and NutCrackers.

  11. Third Class Lever Input force Output force

  12. Third Class Lever Output force Input force Input force Output force

  13. THIRD CLASS LEVERS • The Input Force is Between the Output force and the Fulcrum. • Samples of Third Class Levers – Broom, Shovel, Fishing Pole, Baseball Bat, and Tongs.

  14. Pulley • A grooved wheel with a rope (or a chain, or even steel cable) wrapped around it. • You can change the direction and the amount of your input force.

  15. Fixed Pulley • A pulley that you attach to a structure. • Changes the direction of the input force. • Does not change the amount of force you apply. • Ideal Mechanical Advantage = 1 1

  16. 1

  17. 10N

  18. Movable Pulleys • If you attach a pulley to the object that you wish to move. • I.M.A= 2 • The output force is 2 times the input force you exert on the rope. • You must exert your force over a greater distance.

  19. 1 2

  20. Pulley System • The ideal mechanical advantage of a pulley system is equal to the number of sections of rope that support the object.

  21. 3 1 1 2 2

  22. 10N

  23. 10N

  24. 10N

  25. 10N

  26. A b c Efficiency?

  27. c b A

  28. A b

  29. A b

  30. Gears • Two or more wheels linked together by interlocking teeth.

  31. Compound Machine • A machine that utilizes two or more simple machines.

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