# 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) |