The rise angle of the spring coils (the angle between the coils and the base of the spring) is found from the arctangent of the coil-pitch divided by the spring circumference,
The solid height of the spring is found by summing the widths of all the spring coils. The total number of spring coils is equal to the active coils in the spring interior plus the 2 coils at the spring ends (),
There are several types of springs. One of the most common consists of wire wound into a cylindrical or conical shape. An extension spring is a coiled spring whose coils normally touch each other; as a force is applied to stretch the spring, the coils separate. In contrast, a compression spring is a coiled spring with space between successive coils; when a force is applied to shorten the spring, the coils are pushed closer together. A third type of coiled spring, called a torsion spring, is designed so the applied force twists the coil into a tighter spiral. Common examples of torsion springs are found in clipboards and butterfly hair clips.
Springs are great for storing or absorbing . When you use apushing or pulling force to stretch a spring, you're usinga force over a distance so, in physics terms, you're doing work andusing energy. The tighter the spring, the harder it is to deform, themore work you have to do, and the more energy you need. The energyyou use isn't lost: most of it is stored as potential energy in thespring. Release a stretched spring and you can use it to do work you. When you wind a mechanical clock or watch, you're storing energyby tightening a spring. As the spring loosens, the energy is slowlyreleased to power the inside and turn the hands around theclockface for a day or more. Catapults and crossbows work in asimilar way except that they use twists of elastic for their springsinstead of coils and spirals of metal.