CBSE Questions for Class 11 Engineering Physics Mechanical Properties Of Fluids Quiz 4 - MCQExams.com

The area of cross-section of the wider tube shown in figure is $$800{ cm }^{ 2 }$$. if mass of $$12 kg$$ is placed on the massless piston, the difference in heights h in the level of water in the two tubes is:
  • $$10 cm$$
  • $$6 cm$$
  • $$15 cm$$
  • $$2 cm$$
The diagram (fig.) shows a venturimeter, through which water is flowing. The speed of water at X is 2 cm/sec. The speed of water at Y (taking $$g=1000 cm/sec^2)$$ is:
119850_9f90fd3e6e0648aeb718c4d8e572f30d.png
  • 23 cm/sec
  • 32 cm/sec
  • 101 cm/sec
  • 1024 cm/sec
Which of the following is the incorrect graph for a sphere falling in a viscous liquid? (Given at $$t=0$$, velocity $$v=0$$ and displacement $$x=0$$)
A long capillary tube of radius '$$r$$' initially just vertically completely imerged inside a liquid of angle of contact $${ 0 }^{ \circ  }$$. If the tube is slowly raised then relation between radius of curvature of miniscus inside the capillary tube and displacement $$(h)$$ of tube can be represented by
A solid metallic sphere of radius $$r$$ is allowed to fall freely through air. If the frictional resistance due to air is proportional to the cross-sectional area and to the square of the velocity, then the terminal velocity of the sphere is proportional to which of the following?
  • $${ r }^{ 2 }$$
  • $$r$$
  • $${ r }^{ { 3 }/{ 2 } }$$
  • $${ r }^{ { 1 }/{ 2 } }$$
A tube is attached as shown in closed vessel containing water. The velocity of water coming out from a small hole is

125846.png
  • $$\sqrt { 2 } m/s$$
  • $$2 m/s$$
  • Depends on pressure of air inside vessel
  • None of these
The displacement of a ball falling from rest in a viscous medium is plotted against time. Choose a possible option:
A water barrel stands on a table of height $$h$$. If a small hole is punched in the side of the barrel at its base, it is found that the resultant stream of water strikes the ground at a horizontal distance $$R$$ from the barrel. The depth of water in the barrel is
  • $$\cfrac { R }{ 2 } $$
  • $$\cfrac { { R }^{ 2 } }{ 4h } $$
  • $$\cfrac { { R }^{ 2 } }{ h } $$
  • $$\cfrac { h }{ 2 } $$
A large tank is filled with water (density$$= { 10 }^{ 3 } kg/{ m }^{ 3 }$$). A small hole is made at a depth $$10 m$$ below water surface. the range of water issuing out of the hole is R on ground. What extra pressure must be applied on the water surface so that the range becomes $$2R$$ ( take $$1atm={ 10 }^{ 5 } Pa$$ and  $$g=10 m/{ s }^{ 2 }$$)

126048_35eb0ce946784a75963496e65542fec0.png
  • $$9 atm$$
  • $$4 atm$$
  • $$5 atm$$
  • $$3 atm$$
 Water is flowing steadily through a horizontal tube of non-uniform cross-section.If the pressure of water is $$4\times10^4N/mm^2$$ at a point when cross section is $$0.02m^2$$ velocity of flow is 2m/s what is pressure at a point where cross section reduces to $$0.01m^2$$.
  • $$1.4\times { 10 }^{ 4 } N{ m }^{ 2 }$$
  • $$3.4\times { 10 }^{ 4 } N{ m }^{ 2 }$$
  • $$2.4\times { 10 }^{ -4 } N{ m }^{ 2 }$$
  • none of these
Equal volumes of two immiscible liquids of densities $$\rho$$ and $$2\rho$$ are filled in a vessel as shown figure. Two small holes are punches at depth $$h/2$$ and $$3h/2$$ from the surface of lighter liquid. If $${ v }_{ 1 }$$ and $${ v }_{ 2 }$$ are the velocities of a flux at these two holes then $${ v }_{ 1 }/{ v }_{ 2 }$$ is :

126058_d0b68670265d4eea99f911c0b1594f4d.png
  • $$\dfrac { 1 }{ 2\sqrt { 2 } } $$
  • $$\dfrac { 1 }{ 2 } $$
  • $$\dfrac { 1 }{ 4 } $$
  • $$\dfrac { 1 }{ \sqrt { 2 } } $$
A rectangular tank is placed on a horizontal ground and is filled with water to a height $$H$$ above the base. A small hole is made on one vertical side at a depth $$D$$ below the level of water in the tank. The distance $$x$$ from the bottom of the tank at which the water jet from the tank will hit the ground is
  • $$2\sqrt { D(H-D) } $$
  • $$2\sqrt { DH } $$
  • $$2\sqrt { D(H+D) } $$
  • $$\cfrac { 1 }{ 2 } \sqrt { DH } $$
A water tank is filled with water upto height H. A hole is made in a tank wall at a depth D from the surface of water. The distance X from the lower end of wall where the water stream from tank strikes the ground is:
  • $$2 \sqrt {gD}$$
  • $$2 \sqrt {D \left ( H + D \right)}$$
  • $$2 \sqrt {D \left ( H - D \right)}$$
  • $$\sqrt D$$
To measure the radius of the drop Millikan used _____ law of freely falling drops.
  • Poiseuille's
  • Ostwald's
  • Brewester's
  • Stoke's
A spherical ball is dropped in a long column of a viscous liquid. The speed $$v$$ of ball as a function of time may be best represented by graph
The difference of two liquid levels in a manometer is $$10 cm$$ and its density is $$0.8  gm/cm^3$$. If the density of air is $$1.3 \times 10^3 gm/cm^3$$ then the velocity of air will be (in $$cm/s$$)
  • $$347$$
  • $$34.7$$
  • $$3470$$
  • $$0.347$$
Water flows through two identical tubes $$A$$ and $$B$$. A volume $$V_{0}$$ of water passes through the tube $$A$$ and $$2 V_{0}$$  through $$B$$ in a given time. Which of the following may be correct?
  • Flow in both the tubes are steady
  • Flow in both the tubes are turbulent
  • Flow is steady in $$A$$ but turbulent in $$B$$
  • Flow is steady in $$B$$ but turbulent in $$A$$
A barometer tube, containing mercury, is lowered in a vessel containing mercury until only $$50 cm$$ of the tube is above the level of mercury in the vessel. If the atmospheric pressure is $$75 cm$$ of mercury, what is the pressure at the top of the tube
  • $$33.3 kPa$$
  • $$66.7kPa$$
  • $$3.33 MPa$$
  • $$6.67 MPa$$
Water rises in a vertical capillary tube upto a length of $$10cm.$$ If the tube is inclined at $$45^o$$, the length of water risen in the tube will be,
  • $$10 cm$$
  • $$10 \sqrt2 cm$$
  • $$\displaystyle \dfrac {10}{\sqrt2}$$
  • none of these
The height of water level in a tank is $$H$$. The range of water stream coming out of a hole at depth $$\dfrac{H}{4}$$ from upper water level will be.
  • $$\displaystyle \frac {\sqrt 3 H}{2}$$
  • $$\displaystyle \frac {2H}{\sqrt 3}$$
  • $$\displaystyle \frac {H}{\sqrt 3}$$
  • $$\sqrt 3 H$$
Two equal drops are falling through air with a steady velocity of $$5 cms^{-1}$$. If the drop coalesces, the new terminal velocity will become:
  • $$5 \times 2 cms^{-1}$$
  • $$5 \times \sqrt 2 cms^{-1}$$
  • $$5 \times (4)^{\frac {1}{3}} cms^{-1}$$
  • $$\displaystyle \frac {5}{\sqrt 2} cms^{-1}$$
The diagram shows a venturimeter through which water is flowing. The speed of water $$X$$ is $$2 \ \text{cms}^{-1}$$. The speed of water at $$Y$$ $$(\ taking\ g = 10 \text{ms}^{-2})$$ is

145850.jpg
  • $$23\ \text{cms}^{-1}$$
  • $$32\ \text{cms}^{-1}$$
  • $$101\ \text{cms}^{-1}$$
  • $$1024\ \text{cms}^{-1}$$
There is a small hole of diameter 2 mm in the wall of a water tank at a depth of 10 m below the free water surface. The velocity of efflux of water from the hole will be:
  • 0.14 m/s
  • 1.4 m/s
  • 0.014 m/s
  • 14 m/s
Water stored in a tank flows out through a hole of radius 1mm at a depth 10 m below the surface of water.The rate of flow of water in $$m^3 /s$$ will be
  • $$4.4 \times 10^{-5}$$
  • $$4.4 \times 10^{-4}$$
  • $$4.4 \times 10^{-3}$$
  • $$4.4 \times 10^{-2}$$
One end of a horizontal pipe is closed with the help of a valve and the reading of a barometer attached to the pipe is $$3 \times 10^5$$ pascal. When the valve in the pipe is opened then the reading of the barometer falls to $$10^5$$ pascal. The velocity of water flowing through the pipe will be in m/s.
  • $$0.2$$
  • $$2$$
  • $$20$$
  • $$200$$
Bernoulli's equation includes as a special case:
  • Archimede's principle
  • Pascal's law
  • Toricelli's law
  • Hooke's law
Water flows steadily through a horizontal tube of variable cross-section. If the pressure of water is p at a point where the velocity of flow is v, what is the pressure at another point where the velocity of flow is 2v; $$\rho$$ being the density of water?
  • $$p - \displaystyle \frac {3}{2} \rho v^2$$
  • $$p + \displaystyle \frac {3}{2} \rho v^2$$
  • $$p - 2 \rho v^2$$
  • $$p + 2 \rho v^2$$
A spherical ball falls through viscous medium with terminal velocity $$v$$. If this ball is replaced by another ball of the same mass but half the radius, then the terminal velocity will be (neglect the effect of buoyancy)
  • $$v$$
  • $$2v$$
  • $$4v$$
  • $$8v$$
Water is floating smoothly through a closed-pipe system. At one point A, the speed of the water is 3.0 m/s while at another point B, 1.0 m higher, the speed is 4.0 m/s. The pressure at A is 20 kPa when the water is flowing and 18 kPa when the water flow stops. Then
  • the pressure at B when water is flowing is 6.5 kPa
  • the pressure at B when water is flowing is 8.0 kPa
  • the pressure at B when water stops flowing is 10 kPa
  • the pressure at B when water stops flowing is 8.0 kPa
Two liquid jets coming out of the small holes at P and Q intersect at the point R. Find the position of R if we maintain the liquid level constant

156709.png
  • $$\sqrt 2h$$
  • $$2\sqrt 2h$$
  • $$3\sqrt 2h$$
  • $$5\sqrt 2h$$
A tank of large base area is filled with water up to a height of $$5\ m$$. A hole of $$2\ cm^{2}$$ cross section section in the bottom allows the water to drain out in continuous streams. For this situation, mark out the correct statement(s) (take $$\rho_{water} = 1000\ kg/^{2}, g = 10\ m/s^{2})$$.
157981_20005231fd3a49b5a1fcb6e50c57d82b.png
  • The cross sectional area of the emerging stream of water decreases as it falls down
  • The cross sectional area of the emerging stream of water increases as it falls down
  • At a distance of $$5m$$ below the bottom of the tank, the cross-sectional area of the stream is $$1.414 cm^{2}$$
  • At a distance of $$5m$$ below the bottom of the tank, the cross-sectional area of the stream is $$2.86 cm^{2}$$
A pressure meter attached to a closed water tap reads $$1.5\times 10^5\ \text{Pa}$$. When the tap is opened, the velocity of flow of water is $$10\ \text{ms}^{-1}$$ and the reading of the pressure meter is
  • $$1.5\times 10^5\ \text{Pa}$$
  • $$3\times 10^5\ \text{Pa}$$
  • $$0.5\times 10^5\ \text{Pa}$$
  • $$10^5\ \text{Pa}$$
In a horizontal pipeline of uniform cross section the pressure falls by $$8N/m^2$$ between two points separated by 1 km. If oil of density $$800 kg/m^3$$ flows through the pipe, find the change in KE per kg of oil at these points.
  • $$10^{-2}J/kg$$
  • $$10^{-3}J/kg$$
  • $$10^{-4}J/kg$$
  • $$10^{-1}J/kg$$
The difference of pressure between two points along a horizontal pipe through which water is flowing is $$1.4 cm$$ of Hg. If due to non-uniform cross section the speed of flow at a point of greater cross section is $$60 cm/s$$, the speed of flow at the other point is
  • $$2 m/s$$
  • less than $$60 cm/s$$
  • not affected by non-uniform cross section
  • greater than $$60 cm/s$$
The meniscus formed by mercury in a test tube is 
  • convex
  • concave
  • no meniscus is formed
  • none of these
The figure shows capillary tube of radius $$r$$ dipped into water. The atmospheric pressure is $$P_{0}$$ and the capillary rise of water is $$h. S$$ is the surface tension for water-glass.
Initially, $$h = 10\ cm$$. If the capillary tube is now inclined at $$45^{\circ}$$, the length of water rising in the tube will be
158118_2c891718fa914e3aa2629d109275ae0e.png
  • $$10 cm$$
  • $$10\sqrt {2} cm$$
  • $$\dfrac {10}{\sqrt {2}}cm$$
  • None of these
The figure shows capillary tube of radius $$r$$ dipped into water. The atmospheric pressure is $$P_{0}$$ and the capillary rise of water is $$h. s$$ is the surface tension for water-glass.
The pressure inside water at the point $$A$$ (lowest point of the meniscus) is
158117_f2f575176d3b4d6ea9018228ef489733.png
  • $$P_{0}$$
  • $$P_{0} + \dfrac {2s}{r}$$
  • $$P_{0} - \dfrac {2s}{r}$$
  • $$P_{0} - \dfrac {4s}{r}$$
The incident intensity on a horizontal surface at sea level from the sun is about $$1 kW m^{-2}$$. Find the ratio of this pressure to atmospheric pressure $$p_0$$ (about $$1\times 10^5 Pa)$$ at sea level.
[Assuming that $$50 %$$ % of this intensity is reflected and $$50 % $$ %  is absorbed]
  • $$5\times 10^{-11}$$
  • $$4\times 10^{-8}$$
  • $$6\times 10^{-12}$$
  • $$8\times 10^{-11}$$
Mercury in a test tube forms ______ meniscus
  • concave
  • convex
  • no
  • cant say
The direction of the excess pressure in the meniscus of a liquid of angle of contact $$2\pi/3$$ is:
  • Upward
  • Downward
  • Horizontal
  • Cannot determined
A small ball (menu) falling under gravity in a viscous medium experiences a drag force proportional to the instantaneous speed u such that $$F_{drag}$$ = Ku. Then the terminal speed of the ball within the viscous medium is:
  • $$ \dfrac {K}{mg}$$
  • $$ \dfrac {mg}{K}$$
  • $$ \sqrt{\dfrac {mg}{K}}$$
  • $$ \left ( \dfrac{mg}{K} \right)^2$$
There is a hole in the bottom of tank having water. If total pressure at bottom is 3 atm (1 atm = $$10^5 N/m^2$$) then the velocity of water flowing from hole is:
  • $$\sqrt{400}m/s$$
  • $$\sqrt{600}m/s$$
  • $$\sqrt{60}m/s$$
  • None of these
A spherical ball of iron of radius $$2\ \text{mm}$$ is falling through a column of glycerine. If densities of glycerine and iron are respectively $$1.3\times 10^3\ \text{kg/m}^3$$ and $$8\times 10^3\ \text{kg/m}^3$$. $$\eta\ {for \ glycerine} = 0.83\ \text{Nm}^{-2}\ \text{sec},$$ then the terminal velocity is:
  • $$0.7\ \text{m/s}$$
  • $$0.07\ \text{m/s}$$
  • $$0.007\ \text{m/s}$$
  • $$0.0007\ \text{m/s}$$
A cylinder is filled with non-viscous liquid of density d to a height $$h_0$$ and a hole is made at a height $$h_1$$ from the bottom of the cylinder. The velocity of the liquid issuing out of the hole is:
  • $$\sqrt{2gh_0}$$
  • $$\sqrt{2g(h_0-h_1)}$$
  • $$\sqrt{dgh_1}$$
  • $$\sqrt{dgh_0}$$
The rain drops falling from the sky neither injure us nor make holes on the ground because they move with:
  • constant acceleration
  • variable acceleration
  • variable speed
  • constant terminal velocity
Two drops of the same radius are falling through air with a steady velocity of $$5\ \text{cm per sec}.$$ If the two drops coalesce, the terminal velocity would be
  • $$10\ \text{cm per sec}$$
  • $$2.5\ \text{cm per sec}$$
  • $$5\times (4)^{1/3}\ \text{cm per sec}$$
  • $$5\sqrt{3}\ \text{cm per sec}$$
In a container having water filled upto a height h, a hole is made in the bottom. The velocity of the water flowing out of the hole is:
  • independent of h
  • proportional to $$h^{1/2}$$
  • proportional to h
  • proportional to $$h^2$$
Which molecule of a liquid has higher potential energy?
  • One at the centre of gravity of the liquid
  • One at maximum distance from centre of gravity of liquid
  • One in the surface film
  • One at the bottom of the vessel
A cylinder of height $$20$$m is completely filled with water. The velocity of efflux of water (in ms$$^{-1}$$) through a small hole on the side wall or the cylinder near its bottom is:
  • $$10$$ m/s
  • $$20$$ m/s
  • $$25.5$$ m/s
  • $$5$$ m/s
For flow of a fluid to be turbulent:
  • fluid should have high density
  • velocity should be large
  • reynold number should be less than 2000
  • both (a) and (b)
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