The Murnaghan equation of state is typically expressed as: P ( V ) = K 0 K 0 ′ [ ( V V 0 ) − − K 0 ′ − − 1 ] . If the reduction in volume under compression is low, i.e., for V / V 0 greater than about 90%, the Murnaghan equation can model experimental data with satisfactory accuracy. Moreover, unlike many proposed equations of state, it gives an explicit expression of the volume as a function of pressure V (P). But its range of validity is limited and physical interpretation inadequate. However, this equation of state continues to be widely used in models of solid explosives. Of more elaborate equations of state, the most used in earth physics is the Birch–Murnaghan equation of state. In shock physics of metals and alloys, another widely used equation of state is the Mie–Grüneisen equation of state.