A cylindrical vessel of height 500 mm has an orifice (small hole) at its bottom. The orifice is initially closed and wateris filled in it up to height H. Now the top is completely sealed with a cap and theorifice at the bottom is opened. Some water comes out from the orifice and the water level in the vessel becomes steady with height of water column being 200 mm. Find the fall in height (in mm) of water level due to opening ofthe orifice.
[Take atmospheric pressure $$= 1.0 \times 10^5 N/m^2$$, density of water $$= 1000 kg/m^3$$ and $$g = 10 m/s^2$$. Neglect any affect of surface tension.]