Simple Machines

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Simple Machines
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Levers

• Fulcrum-the pivot point
• Effort arm-the part of the lever on which the
  effort force is applied
• Resistance arm-the part of the lever that exerts
  the resistance force

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MA of Levers

• length of effort arm divided by the length of the
  resistance arm

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3 Classes of Levers

• First class-teeter totter
• Second class-door
• Third class-broom
• Third class always less than one
• Used to change the direction

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Pulleys

• Pulley is a grooved wheel with a rope running
  along the groove
• Fixed pulley used to change direction of force
  and MA of 1
• Block tackle- combination of pulleys

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MA of pulleys

• Count the support rope
• Count the effort rope only if it pulls up

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Wheel and Axle

• A simple machine consisting of two wheels of
  different sizes that rotate together
• Screw driver, ice cream freezer

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MA of Wheel Axle

• radius of wheel divided by radius of the axle

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Inclined Plane

• A sloping surface used to raise objects

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MA of Inclined Planes

• Length of slope divided by the height of slope

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Screw Wedge

• screw is an inclined plane wrapped around a post
• Wedge is an inclined plane with one or two
  sloping sides

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Using Machines
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Compound Machines

• Combinations of two or more simple machines
• Axe- wedge and lever

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Efficiency

• A measure of how much of the work put into a
  machine is changed into useful work
• Why isnt all of the work inputted useful?
• Why is the efficiency of machines less than 100?

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Power

• The rate at which work is done
• Units of Watts

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The End!!!