Simple Machines
A machine is a device that make one's work easier. One type of machine is a simple machine which does work with just one movement (all machines include at least one type of simple machine). A machine that contains more than one simple machine is called a compound machine, which is a machine that is made up of a combination of two or more simple machines. There are six different classifications of simple machines which are: pulleys, levers, wheel and axels, inclined planes, wedges and screws. Information on all of these machines can be found on their own pages, except for wedges and screws, which can be found on the inclined plane web page (because wedges and screws are types of inclined planes).
A machine's main purpose is to make work easier. Work is described as the amount of force applied to an object over a certain distance. Work must be applied in the direction of the force and is expressed through the formula:
W = Fd
In other words, work is the amount of force applied to a machine times the distance traveled.
There are two types of work, work in and work out (represented by Wi and Wo). Work in is the work done to the machine by the person operating it and work out is the amount of work done by the machine itself. Wi can be represented as
fede (effort force x effort distance)
and work out can be symbolized by
frdr (resistance force x resistance distance)
In an ideal situation, work in is always equal to work out.
Simple Machines allowed the builders of the Great Wall of China to build more quickly and efficiently. Machines such as levers and inclined planes allowed the amount of energy spent to do the work to be decreased. Other machines such as pulleys allowed objects to be transported up and down the wall with greater ease. Wedges were incorporated in the hammers that the Chinese used to pound the earth and all the materials of the Wall together.
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