Simple MachinesLevers

Quizhttp://www.proprofs.com/quiz-school/story.php?title=levers-pulleys-2512

Lever

• A Lever is a beam, free to pivot around a point used to move a load.

1st Class Lever

A lever in which fulcrum is between the load and effort.

2nd Class Lever

A lever in which the load is between the fulcrum and effort.

3rd Class Lever

A lever in which the effort is between the fulcrum and load.

Compound Lever A compound lever consists of one lever operating another.

Compound Lever • A compound lever consists of one lever operating

another. Using theCompound Levers Worksheet they should identify each of the nail clipper’s levers and find the effort, fulcrum and load for each one. Then ask each group to select one compound lever; make a sketch of it showing each of the simple levers; and label the effort, fulcrum and load on each one. Based on this drawing, they should be able to tell the class of each lever. Then ask them to represent the compound lever in their sorting categories.

More compound levers

http://www.citytechnology.org/stuff-that-works/levers-have-a-lot-of-class

The nail clipper is an example of a compound lever. The image below shows the two levers that make it up: the handle and the upper jaw. Notice that the load of the handle is also the effort of the jaw; in other words, the handle is in series with the jaw. From the drawing, it should also be clear that the handle is second-class, while the jaw is third-class.

Some other compound levers are shown to the left. Clockwise starting at the top, these include:a pair of vise grips (1st class lever as input to 1st class lever)•a pizza-tray holder (same as vise grips)•a grapefruit sectioner (1st class lever as input to 3rd class lever)•a tea-bag strainer (reverse of grapefruit sectioner)

a pair of garden shears (2nd class lever as input to 1st class lever)•a pair of tin snips (see Extreme Scissors for an extended discussion)

An interesting issue is how to represent these compound levers in sorting according to first, second- or third-class. One solution is

to use a Venn diagram.