Question

At what depth below the surface of water will pressure be equal to twice the atmospheric pressure? (Atmospheric pressure = 10 $N/c{m}^2$, Density of water = ${10}^{3}kg/m^3$, g $=9.8m/s^2$)

• A. The air inside the balloon was exerting pressure in all directions.
• B. Of acceleration due to gravity.
• C. The air inside it was hot.
• D. None of these.

Answer 1

The correct option is A

The air inside the balloon was exerting pressure in all directions.

At any depth h, pressure is given by $P=P_o+\rho gh$

Here $P_o$ is the pressure at free surface which is equal to $10N/c{m}^2={10}^{5}N/m^2$.

As per the question, $2P_o=P_o+\rho gh$

$\Rightarrow P_o=\rho gh$

$\Rightarrow {10}^5={10}^3\times 9.8\times h$

$\therefore h=10.2m$