# Principle of spring dynamometer

Everyone knows that within the elastic limit, the spring force is proportional to the spring’s deformation (elongation or compression value). It is usually written as:

F=k·x

Among them: “F” means the elastic force of the spring, which is the force applied to the force when the spring deforms.

“X” is the length of the spring that is stretched or shortened. Note that “x” is based on the length of the spring without deformation, that is, x=x’-x0 or x=x0-x’.

“k” is called the stiffness coefficient of the spring. It describes the magnitude of the elastic force generated by the unit deformation. The large value of k indicates that the force required for the deformation unit is large, or the spring is “hard”. k is related to the spring material and length , Thickness, etc. are related. The international unit of k is cattle/meter.

If several identical springs are connected in series or in parallel, the stiffness coefficient of this new spring is no longer the original stiffness coefficient; if we assume that the stiffness coefficient of two springs with both stiffness coefficients k in series is k1, then F=k1·x. Since the elastic force at point a is also F, the two stiffness coefficients of spring 1 can be written as k, and the stiffness coefficient of springs with the same original length in parallel is k2, then there is F=k2·x