Question

A Differential manometer is connected at the points A and Bat the centre of two pipes. The pipe A(left limb) contains a liquid of specific gravity = 1.5 while pipe B (right limb)contains a liquid of specific gravity 0.85. The pressure at A and B are .5  kgf/cm^2 and 1.2 kgf/cm2 respectively. Find the difference in level of mercuru in the differential manometer. A is 2.5m above B and 5 m above the mercury in its own limb. B is 2.5 m above the mercury level in limb A.

(a) 12.7 cm

(b) 25.5 cm

(c) 6.28 cm

(d) 10.85 cm

I have been asked this question during an online exam.

My doubt stems from Measurement of Pressure, Simple and Differential Manometers topic in division Pressure and Its Measurement of Fluid Mechanics

Answer 1

Correct choice is (a) 12.7 cm

Best explanation: Total pressure at the datum line in limb A = Total pressure at the datum line in limb B\

                   0.5*9.81*10000 + 5*9.81*1500 + h*9.81*13600 = 1.2*9.81*10000 + (h+2)*9.81*850

                   After solving,

                  h=12.7 cm.