A horizontal tube OP of length L and of uniform cross-sectional area A is open at end O and has a small hole at the other end P. The tube is filled with a liquid of density p and then rotated about the axis passing through O with an angular velocity w. Find the pres- sure exerted by the liquid at end P at the instant when length L/2 of the liquid is left in the tube.

A horizontal tube OP of length L and of uniform cross-sectional area A is open at end O and has a small hole at the other end P. The tube is filled with a liquid of density p and then rotated about the axis passing through O with an angular velocity w. Find the pres- sure exerted by the liquid at end P at the instant when length L/2 of the liquid is left in the tube.