Pressure Prism - Another method in determining the magnitude of the F R and location of cp (graphical technique). - The use of pressure prisms is very convenient for the vertical plane problem. - Consider the pressure distribution along a vertical wall of a tank of width b, which contains a liquid having a specific weight γ. - Since the pressure must vary linearly with depth, we can represent the variation as is shown in Fig. 2.22 (a), where the pressure is equal to zero at the upper surface and equal to γh at the bottom and Fig. 2.22 (b) shows it 3D representation. Fig. 2.22 : The pressure prism