2-2 The speed of sound
Formula - Bulk modulus
The bulk modulus of a medium is the property of the
medium that determines the fractional change in a volume of the medium when the pressure on
A higher bulk modulus indicates a
less compressible medium. For example, steel has a bulk modulus of 160
x 109 Pa while air has a bulk modulus of about 105 Pa.
The bulk modulus is always
positive. Increasing the pressure (Dp > 0)
causes a decrease in the volume (DV < 0) and decreasing the pressure
(Dp < 0) causes an increase in the volume (DV
The SI unit of bulk modulus is the same as that of
pressure N/m2 or Pascal (Pa).
DV/V is the fractional change in the volume
produced by a change in pressure by Dp.