Results of using the Newtonian approximation to obtain the pressure normal to the magnetopause associated with the solar wind static and dynamic pressures (p _i and p _sw) and assuming the boundary is in pressure equilibrium with the internal pressure we compute the energy density ω at all locations in the magnetospheric tail between X _GSE = 0 and X _GSE = −50 R _E. The top panel shows the average value of ω at a given X _GSM for various combinations of the model inputs IMF B _z and dipole tilt ϕ. The red and blue lines are for ϕ = 0 and B _z = −6 nT and 0, respectively. The pink and dashed red and cyan and dashed blue are the corresponding variations for ϕ = −33° and ϕ = +33°. The middle panel shows the difference in mean energy density for the B _z = −6 nT and B _z = 0 cases, δ〈ω〉, the black, green and dashed lines being for ϕ = 0, ϕ = +33° and ϕ = −33°, respectively. The bottom panel shows the rise δ〈ω〉 as a ratio of its value for B _z = 0, δ〈ω〉/〈ω〉 _Bz=0.