Pressure equilibrium
= Pressure equilibrium
{title2=$p_1=p_2$}
Two <fluids> at a stationary, freely movable interface require equal <pressures> when <surface tension> and other <normal stresses> are negligible. This local <pressure equilibrium> does not require equal <temperatures> or <mass densities>. Curvature with nonzero <surface tension> or an applied load changes the normal-stress balance. Comparing points at different heights also requires the <hydrostatic equilibrium> condition.