Question

A submarine is stranded on the bottom of the ocean with its hatch 25 m below the surface. Calculate the force needed to open the hatch from the inside, given it is circular and 0.55 m in diameter. Air pressure inside the submarine is 1.00 atm.

Answer 1

Sol::
Given
Diameter D= 0.55 m
Height h=25 m

Using sea water density =1,025 kg/m^3

Pressure above hatch = (1,025 x g x 25 m)
= 251,125 Pa (g = 9.8 used).

Neglect the pressure inside the submarine, because it is equal to the air pressure at the surface.

Area of hatch = π r^2
= π*0.275^2
= 0.2375 m^2.

Force required to open hatch
F = (251,125 x 0.2375)
= 59642.18 N
or 59.642 KN

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