Question

The vessel shown in the figure has two sections. The lower part is a rectangular vessel with area of crosssection A and height h. The upper part is a conical vessel of height h with base area ‘A’ and top area ‘a’ and the walls of the vessel are inclined at an angle 30º with the 

vertical. A liquid of density ρ fills both the sections up to a height 2h. Neglecting atmospheric pressure,

(A) The force F exerted by the liquid on the base of the vessel is 2hρg(A+a)/2

(B) The pressure P at the base of the vessel is 2hρg A/a

(C) the weight of the liquid W is greater than the force exerted by the liquid on the base. 

(D) the walls of the vessel exert a downward force (F-W) on the liquid. 

Answer 1

Correct Option (D) the walls of the vessel exert a downward force (F-W) on the liquid.

Explanation:

 Force exerted by liquid = ρg (2h).A = F

weight of liquid is W Force exerted by liquid on walls = F – W (upwards) 

So force exerted by the walls on the liquid = (F – W) downwards