At two points on a horizontal tube of varying cross-section the radii are 1 cm and $\mathbf{0 . 4 ~ c m}$, velocities of fluid are $\mathrm{V}_1, \mathrm{~V}_2$ and pressure difference ( $P_1-P_2$ ) between these points is 4.9 cm of water. The value of $\sqrt{V_2^2-V_1^2}$ is ( $\mathrm{g}=$ acceleration due to gravity $\mathrm{g}=980 \mathrm{~cm} / \mathrm{s}^2$ )

Water rises up to height ' $x$ ' in a capillary tube immersed vertically in water. When the whole arrangement is taken to a depth 'd' in a mine, the water level rises height ' $Y$ '. If ' $R$ ' is the radius of earth then the ratio $(\mathrm{Y} / \mathrm{x})$ is

Water is flowing through a horizontal pipe in a streamline flow. At the narrowest part of the pipe

Work done to get ' $n$ ' spherical drops of equal size from a single spherical drop of water, is proportional to