# 13.7.1.3: Gravity Pressure Loss

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Gravity was discussed in Chapter 4 and is

$\left.\dfrac{dP}{dx} \right|_{g} = g\,\rho_m\, \sin\theta \label{phase:eq:Pgravity}$

The density change during the flow can be represented as a function of density. The density in equation (38) is the density without the "movement'' (the "static'' density).