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. \(5500\)
Subtopic:  Viscosity |
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If two glass plates have water between them and are separated by very small distance (see figure), it is very difficult to pull them apart. It is because the water in between forms a cylindrical surface on the side that gives rise to lower pressure in the water in comparison to the atmosphere. If the radius of the cylindrical surface is \(R\) and the surface tension of water is \(T\) then the pressure in water between the plates is lower by:
   
1. \(\frac{2{T}}{{R}}\)
2. \(\frac{4{T}}{{R}}\)
3. \(\frac{{T}}{4{R}}\)
4. \(\frac{{T}}{{R}}\)
Subtopic:  Surface Tension |
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Two tubes of radii \({r}_1\) and \({r}_2,\) and length \({l}_1\) and \({l}_2,\) respectively, are connected in series and a liquid flows through each of them in streamlined conditions. \({P}_1\) and \({P}_2\) are pressure differences across the two tubes. If \({P}_2\) is \(4{P}_1\) and \({l}_2\) is \(\frac{{l}_1}{4},\) then the radius \({r}_2\) will be equal to:
1. \(2{r}_1\)

2. \(\dfrac{{r}_1}{2}\)

3. \(4{r}_1\)

4. \({r}_1\)
Subtopic:  Types of Flows |
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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/m3, coefficient of viscosity of water = 1 m Pa s)
1.  104
2. 103
3. 102
4.  10

Subtopic:  Viscosity |
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If \(M\) is the mass of water that rises in a capillary tube of radius \(r,\) then mass of water which will rise in a capillary tube of radius \(2r\) is:
1. \(M\)
2. \(4M\)
3. \(M/2\)
4. \(2M\)
 

Subtopic:  Capillary Rise |
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A wooden block is initially floating in a bucket of water with \(\frac{4}{5}\)​ of its volume submerged. When a certain amount of oil is poured into the bucket, the block is found to be just under the oil surface with half of its volume submerged in water and half in oil. What is the density of the oil relative to that of water?
1. \(0.7\)
2. \(0.5\)
3. \(0.8\)
4. \(0.6\)

Subtopic:  Archimedes' Principle |
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Water from a tap emerges vertically downwards with an initial speed of 1.0 ms–1. The cross-sectional area of the tap is 10–4 m2. Assume that the pressure is constant throughout the stream of water and that the flow is streamlined. The cross-sectional area of the stream, 0.15 m below the tap would be: (Take g = 10 ms–2)
1. 5 × 10–4m2
2. 2 × 10–5m2
3. 5 × 10–5m2
4. 1 × 10–5 m2

Subtopic:  Bernoulli's Theorem |
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A submarine experiences a pressure of 5.05 × 106 Pa at a depth of d1 in a sea. When it goes further to a depth of d2, it experiences a pressure of 8.08 × 106 Pa. Then d2 - d1 is approximately: (density of water = 103 kg/m3 and acceleration due to gravity = 10 ms–2)
1.  600 m
2. 400 m
3. 300 m
4. 500 m

Subtopic:  Pressure |
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A cubical block of side \(0.5\) m floats on water with \(30\)% of its volume under water. What is the maximum weight that can be put on the block without fully submerging it underwater?
(take, density of water \(=10^3\) kg/m3)
1. \(30.1\) kg
2. \(87.5\) kg
3. \(65.4\) kg
4. \(46.3\) kg

Subtopic:  Archimedes' Principle |
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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 |
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