A cylindrical vessel of cross-sectional area $1000{\mathrm{cm}}^2,$ is fitted with a frictionless piston of mass 10 kg, and filled with water completely. A small hole of cross-sectional area $10{\mathrm{mm}}^2$ is opened at a point 50 cm deep from the lower surface of the piston. The velocity of efflux from the hole will be $(\mathrm{g}=10\mathrm{m}/{\mathrm{s}}^2)$