Machines

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Machines

• Making Work Easier

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What Is A Machine?

• A machine is a device that makes work easier

• Examples
• Doorknob
• Pencil Sharpener
• Knife
• Crow Bar
• Axe

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Simple Machines

• Simple machines are devices that do work with
  only one movement
• There are six types of simple machines
• Levers
• Pulleys
• Wheel and axle
• Inclined plane
• Wedge
• Screw

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Pictures
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Advantages of Simple Machines

• They help us overcome friction and gravity
• A crowbar could help us move a heavy rock or pry
  the lid off a wooden crate
• Machines make work easier by changing the force
  you exert in size, direction or both

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Effort and Resistance Forces

• The force applied to the machine is called the
  effort force (Fe)
• The force applied by the machine to overcome
  resistance is called the resistance force (Fr)

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Forces cont.

• Sketch

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Two Kinds of Work

• There is work done on the machine (Win)
• There is also work done by the machine (Wout)
• WinFexde
• WoutFrxdr

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Ideal Machine

• If there was a perfect machine with out energy
  being lost to friction and heat then work input
  would equal work output
• perpetual machines - Google Search

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The Lever

• A lever is a simple machine that consists of
  three parts
• An effort arm
• A Resistance arm
• A fulcrum

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Sketch in Notes

• Fulcrum
• Effort Arm
• Resistance Arm

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Levers

• There are three kinds of levers
• 1st class
• 2nd Class
• 3rd Class

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1st Class Lever

• The 1st class lever has the fulcrum in the middle
  of the two arms
• Examples are the see-saw, can openers, and
  scissors

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Sketch
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2nd Class Levers

• 2nd class levers have the resistance and effort
  arms on one end, and the fulcrum on the other.
  The resistance is in the middle here

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Sketch
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3rd Class Levers

• The 3rd class has the fulcrum on one end and the
  arms on the other, except reversed. Now the
  effort arm is in the middle

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Sketch
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Pulleys

• A pulley is like a 1st class lever
• There is a fulcrum in the middle (the wheel) and
  a resistance rope and effort rope
• Pulleys can be fixed or movable

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Fixed pulley
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Movable Pulley
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Block and Tackle
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Compound Machines

• A machine made up of several simple machines make
  up a compound machine
• Examples are a bicycle, a lawnmower, or a pencil
  sharpener