Question

The unit coefficient of permeability is ______

(a) cm

(b) s

(c) cm/s

(d) cm/s^2

This question was addressed to me in an international level competition.

Query is from Permeability in section Permeability of Geotechnical Engineering I

Answer 1

Right choice is (c) cm/s

The explanation is: Consider velocity in cm/s,

The hydraulic gradient i=(h/L), where both h and L are in cm.

By Darcy’s law,

V=ki

K=v/i

Considering its units,

K=(cm/s)/(cm/cm)

∴ K=(cm/s)

Hence, coefficient of permeability has same units as velocity.