Hello, my name is huaersai

　　In our life, springs have different forms and serve us everywhere. The common spring is spiral, called coil spring. The spring scale used in the mechanical experiment and the spring of the chest expander are all spiral springs. The coil spring has long and short, thick and thin: the spring of the chest expander is thicker and longer than that of the spring scale; the spring in the drawer lock is short and thin, about several millimeters long; there is a spring washer used to fasten the nut, only one ring of which can not be separated when fastening the screw and nut. When the coil spring is stretched or compressed, it must produce the elastic force against the external force, and within the elastic limit, the larger the shape is, the greater the elastic force will be; once the external force disappears, the shape will also disappear. Some springs are made into sheet or plate shape, called reed or leaf spring. In the harmonica and accordion, there is a kind of copper voice reed. In many electrical switches, there is also a notice reed. In the clocks and watches of toys, there is a spring made of Sergio steel. Under the trucks, there is also a spring made of steel. When they bend, they tend to return to their original shape. The more they bend, the stronger the tendency. There are springs that coil like mosquito repellent incense. For example, these springs are installed in electrical measuring instruments (galvanometer, voltmeter) in the laboratory and in mechanical clocks and watches. When the spring is twisted, it also tends to return to its original shape, which is called torsion spring。