Question

A submarine is stranded on the bottom of the ocean with its hatch 23 m below the surface. Calculate the force needed to open the hatch from the inside, given it is circular and 0.42 m in diameter. Air pressure inside the submarine is 1.00 atm

Answer 1

The pressure of water:

$$p=\rho gh.$$

Force required to open the hatch:

$$F=pA=\rho ghA=\rho gh\frac{\pi d^2}{4}.\\\space\\ F=31230\text{ N}.$$