Question

The pressure of the confined air in the right leg is $P_1$. If the atmospheric pressure is $P$, then

• A. $P$ is equal to $P_1$
• B. $P$ is less than $P_1$
• C. $P$ is greater than $P_1$
• D. $P$ may be less or greater than $P_1$ depending on the mass of the confined air

Answer 1

The correct option is B $P$ is less than $P_1$

According to the question, we can draw the figure as given

Now,
Pressure at point $A=P_1$ (Hydrostatic paradox)
and we know that when we go below the water level pressure of the liquid increases and it is given as
$P+{\rho }_{w}gh=$ pressure at $A=P_1$

Or,
$\Rightarrow P=P_1-{\rho }_{w}gh$
So, $P$ < $P_1$

Hence the P is less than $P_1$