Q. No.Sixty four rain drops of radius \(1 ~\text{mm}\) each falling down with a terminal velocity of \(10~\text{cm/s}\) coalesce to form a bigger drop. The terminal velocity of bigger drop is: (in \(\text{cm/s}\))
1. \(120\)
2. \(125\)
3. \(150\)
4. \(160\)
1. \(120\)
2. \(125\)
3. \(150\)
4. \(160\)
Subtopic: Viscosity |
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In the experiment for measurement of viscosity \(η\) of given liquid with a ball having radius \(R,\) consider following statement.
Choose the correct answer from the options given below:
1. C, D and E only
2. B, D and E only
3. A, C and D only
4. A, B and E only
| A. | Graph between terminal velocity \(V\) and \(R\) will be a parabola. |
| B. | The terminal velocities of different diameter balls are constant for a given liquid. |
| C. | Measurement of terminal velocity is dependent on the temperature. |
| D. | This experiment can be utilized to assess the density of a given liquid. |
| E. | If balls are dropped with some initial speed, the value of \(\eta\) will change. |
1. C, D and E only
2. B, D and E only
3. A, C and D only
4. A, B and E only
Subtopic: Viscosity |
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A small rigid spherical ball of mass \(M\) is dropped in a long vertical tube containing glycerine. The velocity of the ball becomes constant after some time. If the density of glycerine is half of the density of the ball, then the viscous force acting on the ball will be: (consider \(g\) as acceleration due to gravity)
1. \(\dfrac {Mg}{2}\)
2. \(\dfrac {3}{2} Mg\)
3. \(2Mg\)
4. \(Mg\)
1. \(\dfrac {Mg}{2}\)
2. \(\dfrac {3}{2} Mg\)
3. \(2Mg\)
4. \(Mg\)
Subtopic: Viscosity |
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A spherical ball of radius \(1 \times 10^{-4}\) m and density \(10^5 \mathrm{~kg} / \mathrm{m}^3\) falls freely under gravity through a distance h before entering a tank of water, If after entering in water the velocity of the ball does not change, then the value of h is approximately: (The coefficient of viscosity of water is \(9.8 \times 10^{-6}{\mathrm{~N} \mathrm{~s} / \mathrm{m}^2}\))
1. \(2296\) m
2. \(2518\) m
3. \(2249\) m
4. \(2396\) mSubtopic: Viscosity |
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A small ball of mass \( m\) and density \(\rho\) is dropped in a viscous liquid of density \(\rho_0.\) After sometime, the ball falls with constant velocity. The viscous force on the ball is :
1. \(\mathrm{mg}\left(\frac{\rho_0}{\rho}-1\right)\)
2. \(\mathrm{mg}\left(1-\rho \rho_0\right)\)
3. \(\mathrm{mg}\left(1+\frac{\rho}{\rho_0}\right)\)
4. \(\mathrm{mg}\left(1-\frac{\rho_0}{\rho}\right)\)
1. \(\mathrm{mg}\left(\frac{\rho_0}{\rho}-1\right)\)
2. \(\mathrm{mg}\left(1-\rho \rho_0\right)\)
3. \(\mathrm{mg}\left(1+\frac{\rho}{\rho_0}\right)\)
4. \(\mathrm{mg}\left(1-\frac{\rho_0}{\rho}\right)\)
Subtopic: Viscosity |
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Out of air and liquid, which substance is more viscous?
| 1. | Air |
| 2. | Liquid |
| 3. | Both have the same viscosity |
| 4. | None of these |
Subtopic: Viscosity |
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When a small spherical ball is dropped into a long cylindrical pipe filled with glycerine, the \(v\) versus \(t\) graph is:
| 1. |  |
2. |  |
| 3. |  |
4. |  |
Subtopic: Viscosity |
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A metal block with a base area of \(0.20~\text{m}^2\) rests on a table with a liquid film of thickness \(0.25~\text{mm}\) between them. When a horizontal force of \(0.1~\text{N}\) is applied, the block moves at a constant speed. If the liquid's viscosity is \(5.0\times10^{-3} ~\text{Pa-s},\) what is the speed of the block?
| 1. | \(35\times 10^{-3}~\text{m/s}\) | 2. | \(25\times 10^{-3}~\text{m/s}\) |
| 3. | \(45\times 10^{-3}~\text{m/s}\) | 4. | \(15\times 10^{-3}~\text{m/s}\) |
Subtopic: Viscosity |
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Six identical small liquid drops, each falling with a terminal velocity of \(10\) m/s, coalesce to form a single larger spherical drop. Assuming the drops fall through the same viscous medium under gravity and obey Stokes' law, what will be the terminal velocity of the larger drop?
| 1. | \(10\times (6)^{1/3}\) m/s | 2. | \(10\times (6)^{2/3}\) m/s |
| 3. | \(5\times (3)^{2/3}\) m/s | 4. | \(10\times (6)^{3}\) m/s |
Subtopic: Viscosity |
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A ball with mass \(m,\) radius \(r,\) and density \(\rho\) is dropped into a liquid with density \(\rho_{0}.\) After a period of motion, the speed of the ball becomes constant, equal to \(v_0.\) The coefficient of viscosity of the liquid is:
| 1. | \(\dfrac{mg}{6\pi rv_0}\left(1-\dfrac{\rho_0}{\rho}\right)\) | 2. | \(\dfrac{mg}{6\pi rv_0}\left(1+\dfrac{\rho_0}{\rho}\right)\) |
| 3. | \(\dfrac{mg}{3\pi rv_0}\left(1+\dfrac{\rho_0}{\rho}\right)\) | 4. | \(\dfrac{mg}{3\pi rv_0}\left(1-\dfrac{\rho_0}{\rho}\right)\) |
Subtopic: Viscosity |
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