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# Spring constant

## Description

Hooke’s law is a principle of physics that states that the force F needed to extend or compress a spring by some distance X is proportional to that distance. That is:F = -k X, where k is a constant factor characteristic of the spring. A coil spring, also known as a helical spring, is a mechanical device, which is typically used to store energy due to resilience and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. It is made of an elastic material formed into the shape of a helix which returns to its natural length when unloaded. Metal coil springs are made by winding a wire around a shaped former – a cylinder is used to form cylindrical coil springs.The coil spring constant k can be calculated by the wire diameter, the number of wraps, the spring’s shear modulus and the diameter of the coil.

Related formulas

## Variables

 k The spring constant (N/m) d The wire diameter (m) G The the spring's shear modulus (Pa) N The number of wraps (dimensionless) D The diameter of the coil (m)