Terminal velocity

If an air bubble of diameter 2 mm rises steadily through a liquid of density 2000 kg/m³ at a rate of 0.5 cm/s, then the coefficient of viscosity of liquid is ________ Poise. (Take $g=10$ m/s²)

A spherical liquid drop of radius $R$ acquires the terminal velocity $v_1$ when falls through a gas of viscosity $\eta$. Now the drop is broken into 64 identical droplets and each droplet acquires terminal velocity $v_2$ falling through the same gas. The ratio of terminal velocities $v_1/v_2$ is ________.

The terminal velocity ($v_t$) of the spherical rain drop depends on the radius (r) of the spherical rain drop as :

The velocity of a small ball of mass 'm' and density $d_1$, when dropped in a container filled with glycerine, becomes constant after some time. If the density of glycerine is $d_2$, then the viscous force acting on the ball, will be :

A water drop of radius 1 $\mu$m falls in a situation where the effect of buoyant force is negligible. Co-efficient of viscosity of air is $1.8\times10^{-5}$ Nsm$^{-2}$ and its density is negligible as compared to that of water $10^6$ gm$^{-3}$. Terminal velocity of the water drop is :

(Take acceleration due to gravity $=10$ ms$^{-2}$)

A small spherical ball of radius 0.1 mm and density $10^4$ kg m$^{-3}$ falls freely under gravity through a distance $h$ before entering a tank of water. If, after entering the water the velocity of ball does not change and it continue to fall with same constant velocity inside water, then the value of $h$ will be ______ m

(Given $g=10$ ms$^{-2}$, viscosity of water $=1.0\times10^{-5}$ N-sm$^{-2}$).

The diameter of an air bubble which was initially 2 mm, rises steadily through a solution of density 1750 kg m$^{-3}$ at the rate of 0.35 cms$^{-1}$. The coefficient of viscosity of the solution is ______ poise (in nearest integer). (the density of air is negligible).

The velocity of a small ball of mass 0.3 g and density 8 g/cc when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is 1.3 g/cc, then the value of viscous force acting on the ball will be $x\times10^{-4}$ N. The value of $x$ is _______. [use g = 10 m/s$^2$]

Consider two solid spheres P and Q each of density $8\ \mathrm{gm\,cm^{-3}}$ and diameters 1 cm and 0.5 cm, respectively. Sphere P is dropped into a liquid of density $0.8\ \mathrm{gm\,cm^{-3}}$ and viscosity $\eta=3$ poiseulles. Sphere Q is dropped into a liquid of density $1.6\ \mathrm{gm\,cm^{-3}}$ and viscosity $\eta=2$ poiseulles. The ratio of the terminal velocities of P and Q is

Two spheres $P$ and $Q$ of equal radii have densities $\rho_1$ and $\rho_2$, respectively. The spheres are connected by a massless string and placed in liquids $L_1$ and $L_2$ of densities $\sigma_1$ and $\sigma_2$ and viscosities $\eta_1$ and $\eta_2$, respectively. They float in equilibrium with the sphere $P$ in $L_1$ and sphere $Q$ in $L_2$ and the string being taut (see figure). If sphere $P$ alone in $L_2$ has terminal velocity $\vec V_P$ and $Q$ alone in $L_1$ has terminal velocity $\vec V_Q$, then

A tiny spherical oil drop carrying a net charge $q$ is balanced in still air with a vertical uniform electric field of strength $\dfrac{81\pi}{7}\times10^5$ V m⁻¹. When the field is switched off, the drop is observed to fall with terminal velocity $2\times10^{-3}$ m s⁻¹. Given $g=9.8$ m s⁻², viscosity of the air $=1.8\times10^{-5}$ N s m⁻² and the density of oil $=900$ kg m⁻³, the magnitude of $q$ is