What Is a Screw?
A screw is a simple machine that consists of an inclined plane wrapped helically around a central cylinder or shaft. Its primary function is to convert rotational motion (torque) into linear motion, typically to fasten objects together or to lift heavy loads.
Section 2: How a Screw Works
The spiral ridges on a screw are called threads. When the screw is turned, these threads engage with a material or a matching groove. This rotational action forces the screw to move along its axis in a straight line. The distance between the threads, known as the pitch, determines how far the screw moves for each complete rotation.
Section 3: A Practical Example
A common wood screw is a perfect example. As you turn it with a screwdriver, its sharp threads cut into the wood and pull the screw deeper. This action creates a strong joining force, fastening two pieces of wood together. Other examples include the lid of a jar, a car jack (screw jack), and the bolt used with a nut.
Section 4: Importance and Mechanical Advantage
Screws are fundamental in construction, engineering, and everyday objects because they provide a significant mechanical advantage. This means a small rotational force can be converted into a much larger linear force. A screw with a finer pitch (threads closer together) offers a higher mechanical advantage, making it easier to drive into a material or lift a heavy object.