Translations of Encyclopedia about Physics

In principle, the main function of all such machinery is that it simplifies certain work, where the amount of work the user may exert is less but the end result is the same. With machinery, the exertion of force is limited or the direction of our exerted force is changed.

Some forms of simple machinery may be a slanted surface, a screw, a wedge, a lever, a wicket, a pulley, or a wheel.

If we pull up a weight along a slanted surface, we require a smaller amount of force to pull that weight upwards than if we were forced to lift it in a vertical line. However, because the path along the slanted surface is longer, it represents only a technical rather than a physical advantage. To clarify, the physical concept of work is made up of the multiple of the exerted force and the length of the path along the slanted surface.

The best example of a wedge is the axe. When an axe falls into a piece of wood, it exerts a greater force than the force exerted on the axe were applied directly to the piece of wood. The force applied when the axe lands on the wood is broken into two parts, which then break the wood apart.

In a sort of way, a screw is a slanted surface which winds along an axis. The winding force converts into a greater force which pulls the screw into the world, or which joins two pieces of wood together.

A pulley changes the direction of a force but not its size.

A hoist creates a technical but not a physical advantage. We exert a smaller amount of force while pulling on the pulley because the weight of the object we are lifting is divided into two, four or more parts, depending on the number of pulleys we are using. However, in the same manner, we must pull two, four or more times the distance.

The principle of a lever is that a smaller amount of energy is required along a larger distance. This keeps the end result the same because the total amount of energy exerted is the product of the weight the force is applied to and the distance of the path along which the force is applied.

Here, too, the use of shafts results in less force exerted along a larger distance. Shafts may also be used to propel a wheel. The joining of differently sized, teethed wheels with a chain can make some work many times easier, such as for example with the different gears on a mountain bike.

In our present daily life, this principle is applied often, for example when lifting heavy objects, with mechanical lifting cranes, excavators, and the most varied of equipment and machinery, from mountain bikes to clocks.