Class of Lever
From DT Online
Description
Levers are the simplest form of mechanism and may date back to the time of the earliest civilisations. By using a stiff branch resting on a log for example, early man would have been able to move heavy loads such as rocks. This is similar to the way we might use Pliers to grip, scissors to cut, or pincers to take out a nail.
Features and Uses
A lever is a rigid beam that can rotate about a fixed point called the fulcrum. An effort applied to one end of the beam will cause a load to be moved at the other. By moving the fulcrum nearer to the load, you can lift a large load with only a little effort. (This is called Mechanical Advantage.)
There are three different classes of lever, each providing different levels of Mechanical Advantage. The levers are referred to as Class 1, Class 2 and Class 3. The different classes vary in the positions the force or effort, load and fulcrum (pivot point) are located along the length of the lever.
Levers may be considered as one of a small group of Basic Machines first defined by early Greek philosophers.
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