Question

The ratio of pressures between the two points A and B located respectively at depth 0.25 m and 0.75 m below a constant level of water in a tank is
1. 1 : 2
2. 1 : 3
3.  1 : 4
4. 1 : 5

Answer 1

Correct Answer - Option 2 : 1 : 3

Explanation

From the hydrostatic law:

Pressure at any point X any height h1, Px = ρgh1

Pressure at any point Y any height h2, Py = ρgh2

Given, 

 Depth of point A = 0.25 m

∴ Pressure at point A = ρ × g × 0.25

 Depth of point B = 0.75 m 

∴ Pressure at point A = ρ × g × 0.75

\(\frac{{{P_A}}}{{{P_B}}} = \frac{{{\rho \times g\times h_A}}}{{{\rho \times g\times h_B}}} =\frac{{h_A}}{h_B}= \frac{{0.25}}{0.75} = \frac{1}{{3}}\)