Freshwater and seawater flowing in parallel horizontal pipelines are connected to each other by adouble U-tube manometer. The densities of freshwater, seawater, mercury and air are given to be rhow=1000kg/m3, rhosw=1035kg/m3, rhoHg=13600kg/m3and rhoAir=1.2kg/m3, respectively. Determine the pressure difference between the two pipelines, in kPa. Can the air column be ignored in the analysis? (why or why not?)