A manometer containing mercury is connected to two points $($A and B$)15$ m apart, on an inclined pipeline conveying water as shown in the figure. The pipeline is straight and slopes at an angle of $150$ with the horizontal. The manometer gives a reading of $150$ mm$.$ Calculate the pressure difference between the two points $($A and B$)$ of the pipeline. $[$specific weight of water $=9\mathrm{.}81$ kN$/$m$3,$ specific gravity of mercury $-13\mathrm{.}6]$