The dimensions of the quantity \(\Large\frac{\eta}{\rho}\) where \(\eta\) is the viscosity and \(\rho\) is the density are:
1. \(\left [ \dfrac{L}{T} \right ]\) 2. \(\left [ \dfrac{L^2}{T} \right ]\)
3. \(\left [ \dfrac{L}{T^2} \right ]\) 4. \(\left [ \dfrac{L^3}{T^2} \right ]\)
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The viscous force on a ball of radius \(1 \mathrm{~mm}\) moving through a liquid of viscosity \(0.2 ~\mathrm{Ns} / \mathrm{m}^2\) at a speed of \(0.07 \mathrm{~m} / \mathrm{s}\) is: 
1. \(2.63 \times 10^{-4} \mathrm{~N}\)
2. \(0.263 \mathrm{~N}\)
3. \(3.48 \times 10^{-4} \mathrm{~N}\)
4. \(0.348 \mathrm{~N}\)
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Two balls of the same material whose radii are in the ratio of \(1: 2\) fall in a liquid. The ratio of their terminal velocities is given by: 
1. \(2: 3\)
2. \(1: 4\)
3. \(3: 2\)
4. \(5: 9\)
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Choose the correct statement among the following:
1. The terminal velocity is directly proportional to the square of the radius of the body.
2. The terminal velocity is inversely proportional to viscosity of the medium.
3. The terminal velocity is proportional to the difference of densities of body and fluid.
4. All of these
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A graph is plotted between the square of radius \(\text{a}\) of a body and the terminal velocity \(v_T\) acquired by the body while falling through a viscous medium. The slope of the graph is given by where terminal velocity is plotted along y-axis and the square of the radius of body along \(x\)-axis: (where symbols have their usual meaning)
1. \(\dfrac{2}{9 \eta}(\sigma-\rho) g\)
2, \(\dfrac{3}{8}(\sigma-\rho) g\)
3. \(\dfrac{9}{2 \eta}(\sigma-\rho) g\)
4. \(\dfrac{2}{9 \eta}(\rho+\sigma) g\)
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A liquid having a coefficient of viscosity \(\eta\) is filled in a container of cross-sectional area \(A. \) If viscous drag between two adjacent layers is \(F_0, \) then the velocity gradient is: 

1. \(\dfrac{A \eta}{F_0}\)

2. \(\dfrac{A^2 \eta}{F_0}\)

3. \(\dfrac{F_0}{\eta A}\)

4. \(\dfrac{F_0^2}{\eta A^2}\)
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An air bubble of radius, \(r\) rises steadily through a liquid of density, \(\mathit{\rho}\) at the rate of \(v\). Neglecting the density of air, the coefficient of viscosity of the liquid is:
1. \(\dfrac{2}{9}\dfrac{{r}^{2}{\rho}{g}}{v}\) 2. \(\dfrac{1}{3}\dfrac{{r}^{2}{\rho}{g}}{v}\)
3. \(\dfrac{1}{9}\dfrac{{r}^{2}{\rho}{g}}{v}\) 4. \(\dfrac{1}{4}\dfrac{{r}^{2}{\rho}{g}}{v}\)
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Spherical balls of radius \(R\) are falling in a viscous fluid of viscosity η with a velocity \(v.\) The retarding viscous force acting on the spherical ball is:

1. directly proportional to \(R\) but inversely proportional to \(v.\)
2. directly proportional to both radius \(R\) and velocity \(v.\)
3. inversely proportional to both radius \(R\) and velocity \(v.\)
4. inversely proportional to \(R\) but directly proportional to velocity \(v.\)

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The terminal speed of a raindrop falling through air depends on:
1. the size of the raindrop
2. the viscosity of air
3. the acceleration due to gravity
4. all of the above
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A spherical water droplet of radius \(1~\mu \text{m}\) falls through air, where the buoyant force can be ignored. The coefficient of viscosity of air is \(1.8 \times 10^{-5} ~\text N ~\text{s} ~\text m^{-2} ,\) and the density of air is negligible compared to that of water (\(10^6~\text{g}~\text{m}^{-3}\)). If \(g=10~\text{m}~\text{s}^{-2},\) what is the terminal velocity of the droplet?
1. \(145.4 \times 10^{-6}~ \text{m s}^{-1} \)
2. \( 118.0 \times 10^{-6} ~ \text{m s}^{-1} \)
3. \( 132.6 \times 10^{-6} ~ \text{m s}^{-1} \)
4. \( 123.4 \times 10^{-6}~ \text{m s}^{-1} \)
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