# In a baro meter as shown in the figure a small hole is made at a point S Density of mercury is $\rho$. The mercury comes out from this hole with speed v equal to

$\begin{array}{1 1} (a)\;\sqrt {2gh} \\ \\ (b)\;\sqrt {2gH} \\ (c)\;\sqrt {2g(H-h)} \\ (d)\;none\;of\;these \end{array}$

The mercury will not come out of this hole as pressure outside of the tube [atmospheric pressure $= \rho g (h+H)]$ is greater than inside the tubes $(=\rho g h)$
Hence d is the correct answer.

edited Feb 18, 2014 by meena.p