Water rises to a height of $10\, cm$ in capillary tube and mercury falls to a depth of $3.1\,cm$ in the same capillary tube. If the density of mercury is $13.6$ and the angle of contact for mercury is $135^o$, the approximate ratio of surface tensions of water and mercury is
$1 : 0.15$
$1 : 3$
$1 : 6$
$1.5 : 1$
Two equal drops are falling through air with a steady velocity of $5\, cm/second$. If two drops coalesce to form one drop then new terminal velocity will be
A given shaped glass tube having uniform cross-section is filled with water and is mounted on a rotatable shaft as shown in figure. If the tube is rotated with a constant angular velocity $\omega $ then
A boat carrying a number of stones is floating in a water tank. If the stones are unloaded into water, the water level in the tank will ............
The diagram (figure) shows a venturimeter, through which water is flowing. The speed of water at $X$ is $2\,cm/s$. The speed of water at $Y$ (taking $g = 1000\,cm/s^2$ ) is ........ $cm/s$
The velocity of small ball of mass $m$ and density $\rho $ when dropped in a container filled with glycerine of density $\sigma $ becomes constant after sometime. The viscous force acting on the ball in the final stage is