# Speed of Sound in Solids - long rods

## Description

The speed of sound is the distance travelled per unit of time by a sound wave propagating through an elastic medium.

The speed of sound for longitudinal waves in stiff materials such as metals is sometimes given for “long, thin rods” of the material in question, in which the speed is easier to measure. In rods where their diameter is shorter than a wavelength, the speed of pure longitudinal waves may be simplified.

This speed of sound for longitudinal waves in long, thin rods will always be slightly less than the 3-D, longitudinal wave speed in an isotropic materials, and the ratio of the speeds in the two different types of objects depends on Poisson’s ratio for the material.

## Variables

c_{l} | speed of sound for longitudinal waves (m/s) |

Y | Young's modulus (pascal) |

ρ | density (kg/m^{3}) |