Question

A single coloumn manometer is connected to a pipe containing a liquid of specific gravity 0.75. Find the pressure in the pipe if the area of reservoir is 250 times the area of tube for the manometer reading. The difference in mercury level is 40 cm. On the left limb the fluid is upto the height of 20 cm.

(a) 10.42 N/cm^2

(b) 5.21 N/cm^2

(c) 2.60 N/cm^2

(d) None of the mentioned

This question was addressed to me in unit test.

Question is taken from Measurement of Pressure, Simple and Differential Manometers in chapter Pressure and Its Measurement of Fluid Mechanics

Answer 1

The correct option is (b) 5.21 N/cm^2

Explanation: Pressure = a/A height × (density of mercury × 9.81-density of fluid × 9.81)+ height in right limb × density of mercury × 9.81 – height in left limb × density of fluid × 9.81

                                 = 5.21 N/cm^2

{ Here a/A = 1/ 250}.