A spherical body of mass $m$ and radius $r$ is allowed to fall in a medium of viscosity $\eta $. The time in which the velocity of the body increases from zero to $0.63\, times$ the terminal velocity $(v)$ is called time constant $\left( \tau \right)$. Dimensionally $\tau $ can be represented by
$\frac{{m{r^2}}}{{6\pi \eta }}$
$\sqrt {\left( {\frac{{6\pi mr\eta }}{{{g^2}}}} \right)} $
$\frac{m}{{6\pi \eta rv}}$
None of the above
The area of cross section of the wides tube shown in the figure is $800\,cm^2$. If a mass of $12\,kg$ is placed on the massless piston, the difference in the heights $h$ in the level of water in two tubes ........ $m$
A large open tank has two holes in the wall. One is a square hole of side $L$ at a depth $y$ from the top and the other is a circular hole of radius $R$ at a depth $4y$ from the top. When the tank is completely filled with water, the quantities of water flowing out per second from both holes are the same. Then, $R$ is equal to
Equal mass of three liquids are kept in there identical cylindrical vessels $A, B $ $\&$ $ C$. The densities are $\rho_A$, $\rho_B$ and $\rho_C$ with $\rho_A < \rho_B < \rho_C$ . The force on base will be maximum in vessel:-
The height to which a cylindrical vessel be filled with a homogeneous liquid, to make the average force with which the liquid presses the side of the vessel equal to the force exerted by the liquid on the bottom of the vessel, is equal to
A homogeneous solid cylinder of length $L(L < H/2)$, cross-sectional area $A/5$ is immersed such that it floats with its axis vertical at the liquid-liquid interface with length $L/4$ in the denser liquid as shown in the figure. The lower density liquid is open to atmosphere having pressure $P_0$. Then, density $D$ of solid is given by