Three points P, Q and R lie inside a large stationary tank completely filled with water. Points P and Q are at exactly the same depth but are separated horizontally by 1 m. Point R is 25 cm deeper than P.
(i) Is the pressure at P equal to that at Q? Give a reason for your answer.
(ii) Compare the pressure at R with the pressure at P. State your reasoning without using any numerical calculation.
(iii) Suppose a tight-fitting horizontal lid of area 0.40 m² is gently loaded with an additional 200 N. Explain qualitatively how the pressures at P, Q and R will change, and whether the difference between the pressures at P and R will remain the same or not.