Question

A U-tube manometer is used to measure the pressure at the stagnation point of a model in a wind tunnel. One side of the manometer goes to an orifice at the stagnation point; the other side is open to the atmosphere (fig. below). If there is a difference of 3 cm in the mercury levels in the two tubes, what is the pressure difference in N/m2 .

Answer 1

Answer:

$\Delta p=4000.4199\ Pa$

Explanation:

Given:

• difference in the column of mercury of u-tube manometer, $\Delta h=3\ cm=0.03\ m$

We know that the pressure due to height if a liquid column is given as:

$p=\rho.g.h$

where:

p = pressure

h = height of the liquid

$\rho=$ density of the liquid

• We have the density of mercury as, $\rho=13593\ kg.m^{-3}$

Now the difference of pressure in the two tubes of the manometer:

$\Delta p=\rho.g.\Delta h$

$\Delta p=13593\times9.81\times0.03$

$\Delta p=4000.4199\ Pa$