A ball of radius $r $ and density $\rho$ falls freely under gravity through a distance $h$ before entering water. Velocity of ball does not change even on entering water. If viscosity of water is $\eta$, the value of $h$ is given by
A ball of radius $r $ and density $\rho$ falls freely under gravity through a distance $h$ before entering water. Velocity of ball does not change even on entering water. If viscosity of water is $\eta$, the value of $h$ is given by
- A
$\frac{2}{9}{r^2}\left( {\frac{{1 - \rho }}{\eta }} \right)\,g$
- B
$\frac{2}{{81}}{r^2}\left( {\frac{{\rho - 1}}{\eta }} \right)\,g$
- C
$\frac{2}{{81}}{r^4}{\left( {\frac{{\rho - 1}}{\eta }} \right)^2}g$
- D
$\frac{2}{9}{r^4}{\left( {\frac{{\rho - 1}}{\eta }} \right)^2}g$
Similar Questions
A water drop of radius $1\,\mu m$ falls in a situation where the effect of buoyant force is negligible. Coefficient of viscosity of air is $1.8 \times 10^{-5}\,Nsm ^{-2}$ and its density is negligible as compared to that of water $10^{6}\,gm ^{-3}$. Terminal velocity of the water drop is________ $\times 10^{-6}\,ms ^{-1}$
(Take acceleration due to gravity $=10\,ms ^{-2}$ )
A water drop of radius $1\,\mu m$ falls in a situation where the effect of buoyant force is negligible. Coefficient of viscosity of air is $1.8 \times 10^{-5}\,Nsm ^{-2}$ and its density is negligible as compared to that of water $10^{6}\,gm ^{-3}$. Terminal velocity of the water drop is________ $\times 10^{-6}\,ms ^{-1}$
(Take acceleration due to gravity $=10\,ms ^{-2}$ )
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