Bulk modulus

Resistance of a material to uniform pressure

The bulk modulus ( K {\displaystyle K} or B {\displaystyle B} or k {\displaystyle k}) of a substance is a measure of the resistance of a substance to bulk compression. It is defined as the ratio of the infinitesimal pressure increase to the resulting relative decrease of the volume. Other moduli describe the material's response (strain) to other kinds of stress: the shear modulus describes the response to shear stress and Young's modulus describes the response to normal (lengthwise stretching) stress.

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