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Q. No.If it takes \(5\) minutes to fill a \(15\) litre bucket from a water tap of diameter \(\frac{2}{\sqrt\pi}~\text{cm},\) then the Reynolds number for the flow is:
(density of water \(=10^3~\text{kg/m}^3\) and viscosity of water \(=10^{-3}~\text{Pa.s}) \)
1. \(11,000\)
2. \(550\)
3. \(1100\)
4. \(5500\)
(density of water \(=10^3~\text{kg/m}^3\) and viscosity of water \(=10^{-3}~\text{Pa.s}) \)
1. \(11,000\)
2. \(550\)
3. \(1100\)
4. \(5500\)
Subtopic: Viscosity |
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Water from a pipe is coming at a rate of 100 liters per minute. If the radius of the pipe is 5 cm, the Reynolds number for the flow is of the order of- (density of water = 1000 kg/, coefficient of viscosity of water = 1 m Pa s)
1.
2.
3.
4. 10
Subtopic: Viscosity |
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From NCERT
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A solid sphere, of radius \(R,\) acquires a terminal velocity \(v_1\) when falling (due to gravity) through a viscous fluid having a coefficient of viscosity \(\eta.\) The sphere is broken into \(27\) identical solid spheres. If each of these spheres acquires a terminal velocity, \(v_2\), when falling through the same fluid, the ratio \(\left(\dfrac{v_1}{v_2}\right) \) equals:
1. \(\dfrac{1}{9}\)
2. \(\dfrac{1}{27}\)
3. \(9\)
4. \(27\)
Subtopic: Viscosity |
68%
From NCERT
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The velocity of the upper layer of water in a river is \(36~\text{kmh}^{-1}.\) Shearing stress between horizontal layers of water is \(10^{-3}~\text{Nm}^{-2}.\) The depth of the river is:
(coefficient of viscosity of water is \(10^{-2}~\text {Pa-s}\) )
1. \(100~\text m\)
2. \(200~\text m\)
3. \(300~\text m\)
4. \(400~\text m\)
(coefficient of viscosity of water is \(10^{-2}~\text {Pa-s}\) )
1. \(100~\text m\)
2. \(200~\text m\)
3. \(300~\text m\)
4. \(400~\text m\)
Subtopic: Viscosity |
89%
From NCERT
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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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Six identical small liquid drops are mixed together to form a bigger drop. The terminal velocity of bigger drop, if the terminal velocity of the small drop is \(10\) m/s, will be:
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
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 |
75%
From NCERT
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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 |
From NCERT
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A liquid drop of radius \(R \) is divided into \(27\) identical drops. If the surface tension of the drops is \(T,\) then the work done in this process is:
1. \(4\pi R^2T \)
2. \(3\pi R^2T\)
3. \(8\pi R^2T\)
4. \(\frac{1}{8}\pi R^2T\)
1. \(4\pi R^2T \)
2. \(3\pi R^2T\)
3. \(8\pi R^2T\)
4. \(\frac{1}{8}\pi R^2T\)
Subtopic: Viscosity |
From NCERT
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A small ball of mass \(\text m\) 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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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 |
JEE
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