Bulk Modulus (B = -p/(ΔV/V) = -pV/ΔV)

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B = -p/(ΔV/V) = -pV/ΔV

What each symbol means

SymbolWhat it stands for
BBulk modulus (Pa)
VOriginal volume (m³)
pHydraulic pressure applied uniformly (Pa)
ΔVChange in volume (m³, negative for compression)

When to use this

Applicable to solids, liquids, and gases. Negative sign ensures B is always positive (pressure increase → volume decrease). Compressibility k = 1/B. Solids have largest B, gases smallest. For water B ≈ 2.2 × 10⁹ Pa, for air B ≈ 1.0 × 10⁵ Pa.