Simple Machines

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Simple Machines
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Types of Simple Machines
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How do machines make work easier?

• Machines make work easier by
• multiplying the size of the force
  you exert (such as in this
  pulley
  system).

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• Machines also make work easier by changing
  direction of the force. Example A force on the
  rope downward, hoists the weight upward.

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What are simple machines?

• A Simple Machine is a device that does work with
  one movement.

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LEVERS

• A lever is a bar that is free to pivot, or turn
  at one fixed point. The fixed point is called a
  fulcrum.

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• The part of the lever on which the effort force
  is applied is called the effort arm.
• The part of the lever that exerts the resistance
  force is called the resistance arm.

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First Class Lever
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Examples of First Class Levers
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Second Class Lever
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Third Class Lever
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PULLEYS

• A pulley is a grooved wheel with a rope or chain
  that works something like a first class lever.

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Comparing pulleys to levers
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Pulleys can be FIXED or MOVABLE.

• The movable pulley has a greater mechanical
  advantage and therefore multiples the effort
  force by a greater amount.

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More pulleys --More rope--Less effort
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WHEEL AND AXLE

• Simple machine consisting of two wheels of
  different sizes that rotate together. The smaller
  wheel is usually called the axle. (Effort force
  usually applied to larger wheel.)

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Gearsmodified wheel axle

• The effort is applied to one gear. The gear
  ratio is found by dividing the radius of the
  effort ear by the radius of the resistance gear.
  (This is the ideal mechanical advantage for the
  gears.)

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The SCREW

• A screw is an inclined plane wrapped in a spiral
  around a cylindrical post.

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The wedge

• A wedge is an inclined plane with one or two
  sloping sides.