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Levers - Simple Machines That Rock The World
From the very ancient times dating back to the ancient Greek civilization, man has been constantly on the lookout of tools that could reduce the amount of effort required to carry out operations such as pushing, pulling and lifting heavy objects. Traditionally, machines have been divided into two categories: simple and complex.
Simple machines are tools that make work easier. They have few or no moving parts. These machines use energy to work.
There are only six simple machines: the lever, pulley, wheel and axle, inclined plane, wedge, and screw. Complex machines, on the other hand, are made up of several simple machines, and are used to perform complex tasks that are not possible to do by humans. For instance, a crane is a complex machine using the many simple machines like the pulley and lever (the arm of the crane), and is used to lift very heavy objects.
As mentioned before, levers are simple machines. A lever is a board or bar that rests on a turning point. This turning point is called the fulcrum. An object that a lever moves is called the load. The closer the object is to the fulcrum, the easier it is to move.
Now, all of us have loved playing on a see-saw swing with our friends or siblings, but did you ever think that a see saw is nothing but a simple lever? A see-saw (or teeter-totter) is a plank of wood, the center of which is hinged on to a bar - the fulcrum. It moves up or down around this rod.
While playing on it, you would have noticed that the heavier person between you and your friend was pushed down as you rose up in the air. Moreover, by applying a little force on the see-saw, you were able to lift a heavier person, thus greatly reducing the amount of effort required to lift the heavier person. To realize the difference in the effort required, try to lift your friend in the air by grabbing him physically.
Another example of a lever is a bottle opener. As you would have seen, it is extremely tough to open a glass soda bottle by hand. By using a bottle opener, we are magnifying the force applied and thus reducing the effort required to do the job.
A similar example can be seen in the form of a hammer which is used to pull a nail out of the wooden block.
Levers are divided into three classes, depending on the location of the fulcrum. A first-class lever is a lever in which the fulcrum is located between the input effort and the output load. Example: see-saw, hammer's claw etc.
In a second class lever the input effort is located at one end of the bar and the fulcrum is located at the other end of the bar, opposite to the input, with the output load at a point between these two forces. Example: Door knob, wrench (used by plumbers and mechanics).
In third class levers, effort is applied between the output load on one end and the fulcrum on the opposite end. Example: Baseball bat, broomstick, etc.
In the modern world we use levers all the time, and usually don't even realize how much easier this simple machine makes our lives.
About the Author Sara Jones was a fine student but science was a source of frustration she didn't want her kids to suffer. She met Rick and Amanda Birmingham and realized their grasp of everyday science was the secret to making science fun. To learn more about the solution to science stress visit www.SuperFunScience.com
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