A container of large uniform cross-sectional area resting on a horizontal surface, holds two immiscible, non-viscous and incompressible liquids of densities and , each of height as shown in the figure. The lower density liquid is open to the atmosphere having pressure . (a) A homogeneous solid cylinder of length , cross-sectional area is immersed such that it floats with its axis vertical at the liquid-liquid interface with length in the denser liquid. Determine: (i) the density of the solid and (ii) the total pressure at the bottom of the container. (b) The cylinder is removed and the original arrangement is restored. A tiny hole of area is punched on the vertical side of the container at a height . Determine : (i) the initial speed of efflux of the liquid at the hole, (ii) the horizontal distance travelled by the liquid initially, and (iii) the height at which the hole should be punched so that the liquid travels the maximum distance initially. Also calculate . (Neglect the air resistance in these calculations.)
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Written solution
Step 1: Determine the density of the solid cylinder.
The cylinder floats in equilibrium at the interface, meaning its weight is balanced by the total buoyant force.
Step 2: Determine the total pressure at the bottom of the container.
The total pressure is the sum of atmospheric pressure and the pressure due to the weight of the liquids and the cylinder.
Step 3: Determine the initial speed of efflux at the hole.
The pressure difference between the inside of the container at height and the atmosphere is calculated.
Step 4: Determine the horizontal distance travelled by the liquid.
The time of flight is determined by the vertical motion from height .
Step 5: Determine the height for maximum distance and calculate .
Maximize the square of the distance with respect to .
Answer:
(a) (i)
(ii)
(b) (i)
(ii)
(iii) ,