A hole of area 5 cm² is formed in the side of a ship 3 m below the water level. What minimum force (in N) is required to hold on a patch covering the hole from the inside of the ship?

$\text{ Here, }h=3\mathrm{m}$

$\begin{array}{l}\therefore P=h\rho g=3\times {10}^3\times 10\\ \left(\because \text{ density of water, }\rho ={10}^3{\mathrm{kgm}}^{-3}\right.\text{ ) }\\ \text{ Area of hole, }A=5{\mathrm{cm}}^2=5\times {10}^{-4}{\mathrm{m}}^2\\ \text{ Therefore, force required to hold a patch covering the hole, }\\ F=P\times A=3\times {10}^3\times 10\times 5\times {10}^{-4}=1.5\times 10\mathrm{N}=15N\end{array}$