Question

Seawater fills a tank to a depth of 12 ft. If the specific gravity of seawater is 1.03 and the atmospheric pressure at this location is 14.8 psi, the absolute pressure (psi) at the bottom of the tank is most nearly:______.
A. 5.4
B. 20.2
C. 26.8
D. 27.2
E. 10.8

Answer 1

Answer: (b)

Explanation:

Given

Depth of tank is $h=12\ ft\ \text{or}\ 3.65\ m$

Specific gravity of seawater is $S.G.=1.03$

Pressure difference due to column of water is

$\Rightarrow \Delta P=\rho gh\\\Rightarrow \Delta P=1.03\times 10^3\times 9.8\times 3.65\\\Rightarrow \Delta P=36.84\times 10^3\ Pa\ \text{or}\\\Rightarrow \Delta P=5.34\ psi$

So, absolute pressure is given by

$\Rightarrow P_{abs}=P_{atm}+\Delta P\\\Rightarrow P_{abs}=14.8+5.34\\\Rightarrow P_{abs}=20.14\approx 20.2\ psi$

Thus, option (b) is correct.