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Mechanical Devices: Everyday Life
Mr Tulk and dog Sausage going fishing using flying fox he built onto other island - Solitary Island, c. 1935 / by Winifred Tulkby State Library of New South Wales collection on Flickr

Simple Machine is a mechanical device that changes the direction or magnitude of a force. One form of a simple machine is the pulley.  Pulleys allow people and materials to move from one place to another much more easily. If Mr. Tulk and his dog, Sausage, had to get across the canyon without a pulley, what would they have to do?
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New Lobster Buoys on the Harbor Wharf (Matinicus Island, ME)by takomabibelot on Flickr

A simple machine uses a single applied force to do work against a single load force.  This pulley is used on docks and piers to help fisherman move lobster traps and heavy bags of clams off of their boats.  Without the pulley, they would have to pick them up and carry them off the boat by hand.
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Trigonometryby jurvetson on Flickr

The basic kinds of simple machines are
  • Lever
  • Wheel and axle
  • Pulley
  • Inclined plane
  • Wedge
  • Screw
They are the elementary "building blocks" of all the complicated machines (sometimes called "compound machines" to emphasize that they are combinations of the simpler building blocks). For example, wheels, levers, and pulleys are all used in the mechanism of a bicycle.

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by pusgums on Flickr

Levers use  the force of moving a stick back and forth at one end to make something happen at the other end.  The handle on this machine is a lever, as are rakes, tire jacks and shovels.  This lever uses the force applied by the man's hand on the effort arm to put the cap on a bottle.  The fulcrum is the point where the moving silver lever is connected to the red part of the machine.
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Fall Laborsby CarbonNYC on Flickr

A rake is another example of a lever.  Moving the top of the rake just a little, can help you to gather a large number of leaves with the toothed end, that is on the ground.  The fulcrum is near the top of the rake where you move it back and forth.  The effort comes from your arms, and the resistance comes from dragging the teeth of the rake across the grass.  Although it is a very simple machine, it allows people to clear their yards without having to pick up all of the leaves with their hands.
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