CBSE Questions for Class 11 Engineering Physics Mechanical Properties Of Fluids Quiz 7 - MCQExams.com

Water containing air bubbles flows without turbulence through a horizontal pipe which has a region of narrow cross-section. In this region the bubbles.
  • Move with greater speed and are smaller than in the rest of the pipe
  • Move with greater speed and are larger in size than in the rest of the pipe
  • Move with lesser speed and are smaller than in the rest of the pipe
  • Move with lesser speed and are of the same size as in the rest of the pipe
When one end of the capillary is dipped in water, the height of water column is $$'h'$$. The upward force of $$105$$ dyne due to surface tension balanced by the force due to the weight of water column. The inner circumference of the capillary is
(Surface tension of water $$= 7\times 10^{-2}N/m)$$
  • $$1.5\ cm$$
  • $$2\ cm$$
  • $$2.5\ cm$$
  • $$3\ cm$$
A particle released from rest is falling through a thick fluid under gravity. The fluid exerts a resistive force on the particle proportional to the square of its speed. Which one of the following graphs best depicts the variation of its speed $$v$$ with time $$t$$?
An open tank filled with water density $$\rho$$ has a narrow hole at a depth of $$h$$ below, then the velocity of water flowing out is:
  • $$h\rho g$$
  • $$2gh$$
  • $$\sqrt{2gh}$$
  • $$gh$$
Equal volume of two immiscible liquids of densities $$\rho$$ and $$2\rho$$ are filled in a vessel as shown in figure. Two small holes are made at depth $$\dfrac {h}{2}$$ and $$\dfrac {3h}{2}$$ from the surface of lighter liquid. If $$v_{1}$$ and $$v_{2}$$ are the velocities of efflux at these two holes, then $$\dfrac{v_{1}}{v_{2}}$$ will be
679161_54054fb17b754a0791008f97c74ad571.png
  • $$\dfrac {1}{\sqrt {2}}$$
  • $$\dfrac {1}{2\sqrt {2}}$$
  • $$\dfrac {1}{2}$$
  • $$\dfrac {1}{4}$$
A cylindrical tank has a hole of $$1$$ $$cm^2$$ m bottom. If the water is allowed to flow into the tank from a tube above it at the rate of $$70cm^2/s$$, then the maximum height up to which water can rise in the tank is?
  • $$2.5$$cm
  • $$5$$cm
  • $$10$$cm
  • $$0.25$$cm
A rectangular vessel when full of water, takes $$10\ min$$ to be emptied through an orifice in its bottom. How much time will it take to be emptied when half filled with water?
  • $$9\ min$$
  • $$7\ min$$
  • $$5\ min$$
  • $$3\ min$$
The pressure at depth $$h$$ below the surface of a liquid of density $$\rho $$ open to the atmosphere is 
  • Greater than the atmospheric pressure by $$\rho gh$$
  • Less than the atmospheric pressure by $$\rho gh$$
  • Equal to the atmospheric pressure
  • Decreases exponentially with depth
  • Increases exponentially with depth
The material of a wire has a density of 1.4 g/cm$$^3$$. If it is not wetted by a liquid of surface tension 44 dyne/cm, then the maximum radius of the wire which can float on the surface of liquid is :
  • $$\dfrac{10}{28} cm$$
  • $$\dfrac{10}{14} cm$$
  • $$\dfrac{10}{7} mm$$
  • 0.7 cm
A tank is filled with water of density 1 g $$cm^{-3}$$ and oil of density 0.9 g $$cm^{-3}$$. The height of water layer is 100 cm and of the oil layer is 400 cm. If g = 980 cm $$s^{-2}$$, then the velocity of efflux from an opening in the bottom of the tank is :
  • $$\sqrt{920\times 980}cms^{-1}$$
  • $$\sqrt{900\times 980}cms^{-1}$$
  • $$\sqrt{1000\times 980}cms^{-1}$$
  • $$\sqrt{92\times 980}cms^{-1}$$
The potential energy of a molecules on the surface of a liquid compared to the one inside the liquid is :
  • Zero
  • Lesser
  • Equal
  • Greater
A liquid is flowing in a horizontal uniform capillary tube under a constant pressure difference p. The value of pressure for which the rate of flow of the liquid is doubled when the radius and length both are doubled, is
  • $$\rho$$
  • $$\displaystyle\frac{3\rho}{4}$$
  • $$\displaystyle\frac{\rho}{2}$$
  • $$\displaystyle\frac{\rho}{4}$$
Water flows along a horizontal pipe whose cross.section is not constant. The pressure is 1 cm of Hg, where the velocity is $$35\, cms^{-1}$$. At a point where the velocity is $$65\, cms^{-1}$$, the pressure will be 
  • 0.89 cm Hg
  • 8.9 cm of Hg
  • 0.5 cm of Hg
  • 1 cm of Kg
A liquid is filled upto a height of $$20\ m$$ in a cylindrical vessel. The speed of liquid coming out of a small hole at the bottom of the vessel is (take, $$g = 10\ ms^{-2}$$).
  • $$1.2\ ms^{-1}$$
  • $$1\ ms^{-1}$$
  • $$2\ ms^{-1}$$
  • $$3.2\ ms^{-1}$$
  • $$1.4\ ms^{-1}$$
A cylindrical vessel of base radius R and height H has a narrow neck of height h and radius r at one end(see figure). The vessel is filled with water(density $$\rho_w$$) and its neck is filled with immiscible oil (density $$\rho_o$$). Then the pressure at :
739173_fe40c5d5773b4c108e69754e942fb21f.png
  • M is $$g(h\rho_o+H\rho_w)$$
  • N is $$g(h\rho_o+H\rho_w)\displaystyle\frac{r^2}{R^2}$$
  • M is $$gH\rho_w$$
  • N is $$g\displaystyle\frac{\rho_wHR^2+\rho_ohr^2}{R^2+r^2}$$
Equal volumes of two immisible liquids of densities $$\rho$$ and $$2\rho$$ are filled in a vessel as shown in figure. Two small holes are punched at depths $$h/2$$ and $$3h/2$$ from the surface of lighter liquid. If $$v_1$$ and $$v_2$$ are the velocities of efflux at these two holes, then $$v_1/v_2$$ is?
693009_52fd398aff604a1ea9a6b002bd88b748.jpg
  • $$\displaystyle\frac{1}{2\sqrt{2}}$$
  • $$1/2$$
  • $$1/4$$
  • $$\displaystyle\frac{1}{\sqrt{2}}$$
A tank of height $$5\ m$$ is full of water. There is a hole of cross sectional area $$1\ cm^2$$ in its bottom. The initial volume of water that will come out from this hole per second is
  • $$10^{-3}m^3/s$$
  • $$10^{-4}m^3/s$$
  • $$10m^3/s$$
  • $$10^{-2}m^3/s$$
A large tank is filled with water to a height H. A small hole is made at the base of the tank. It takes 71 time to decrease the height of water to $$\frac {H}{\eta }(\eta > 1)$$ and $$T_2$$ time to take out the rest of 11 water. If $$T_1 = T_2$$ then the value of $$\eta$$ is 
  • 2
  • 4
  • 6
  • 8
A capillary tube of radius $$r$$ is immersed in water and water rises in it to a height $$h$$. Mass of water in the capillary tube is $$m$$. If the radius of the tube is doubled, mass of water that will rise in the capillary tube will now be
  • $$m$$
  • $$2m$$
  • $$\cfrac { m }{ 2 } $$
  • $$4m$$
Two mercury drops(each of radius r) merge to form a bigger drop. The surface energy of the bigger drop if T is the surface tensions 
  • $$2^{5/3}\pi r^2T$$
  • $$4\pi r^2T$$
  • $$2\pi r^2T$$
  • $$2^{8/3}\pi r^2T$$
A $$20$$cm long capillary tube is dipped in water. The water rises up to $$8$$cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be:
  • $$8$$cm
  • $$6$$cm
  • $$10$$cm
  • $$20$$cm
Water rises in a vertical capillary tube up to a length of $$10$$cm. If the tube is inclined at $$45^o$$, the length of water risen in the tube will be:
  • $$10$$cm
  • $$10\sqrt{2}$$cm
  • $$10/\sqrt{2}$$cm
  • None of these
The heart of a man pumps $$5\ litres $$ of blood through the arteries per minute at a pressure of $$150\ mm$$ of mercury. If the density of mercury be $$13.6\times { 10 }^{ 3 }\ kg/{ m }^{ 3 }$$ and $$g=10\ m/{ s }^{ 2 }$$ then the power of heart in watt is
  • $$1.50$$
  • $$1.70$$
  • $$2.35$$
  • $$3.0$$
A spherical solid ball of volume $$V$$ is made of a material of density $$\rho_{1}$$. It is falling through a liquid of density $$\rho_{1}(\rho_{2} < \rho_{1})$$. Assume that the liquid applies a viscous force on the ball that is proportional to the square of its speed $$v$$, i.e. $$F_{viscous} = kv^{2}(k > 0)$$. The terminal speed of the ball is
  • $$\sqrt {\dfrac {Vg(\rho_{1} - \rho_{2})}{k}}$$
  • $$\dfrac {Vg\rho_{1}}{k}$$
  • $$\sqrt {\dfrac {Vg\rho_{1}}{k}}$$
  • $$\dfrac {Vg(\rho_{1} - \rho_{2})}{k}$$
Depth of sea is maximum at Mariana Trench in West Pacific Ocean. Trench has maximum depth of about $$11km$$. At bottom of trench water column above it exerts $$1000$$ atm pressure. Percentage change in density of sea water at such depth will be around
(Given, $$B=2\times {10}^{9}N{m}^{-2}$$ and $${p}_{atm}=1\times {10}^{5}N{m}^{-2}$$)
  • about $$5$$%
  • about $$10$$%
  • about $$3$$%
  • about $$7$$%
A vertical tank, open at the top, is filled with a liquid and rests on a smooth horizontal surface. A small hole is opened at the center of one side of the tank. The area of a cross-section of the tank is $$N$$ times the area of the hole, where $$N$$ is a large number. Neglect mass of the tank itself. The initial acceleration of the tank is:
  • $$\dfrac {g}{2N}$$
  • $$\dfrac {g}{\sqrt {2}N}$$
  • $$\dfrac {g}{N}$$
  • $$\dfrac {g}{2\sqrt {N}}$$
A sealed tank contains water to a height of 11 m and air at 3 atm. Water  flower out from the bottom of a tank through a small hole. The velocity of efflux is (g=$$10{ ms }^{ -2 }$$)
  • 18.1 $${ ms }^{ -1 }$$
  • 24.2 $${ ms }^{ -1 }$$
  • 20.4 $${ ms }^{ -1 }$$
  • 28.6 $${ ms }^{ -1 }$$
Pressure applied to an enclosed fluid is transmitted undiminished to every point of the fluid and the walls of containing vessel. This law was first formulated by
  • Reynolds
  • Bernoulli
  • Pascal
  • Torricelli
Two syringes of different cross section (without needle) filled with water are connected with a tightly fitted rubber tube filled with water. Diameters of the smaller piston and larger piston are 1 cm and 3 cm respectively. If a force of 10 N is applied to the smaller piston then the force exerted on the larger piston is
  • 30 N
  • 60 N
  • 90 N
  • 100 N
When the flow parameters of any given instant remain same at every point, then flow is said to be
  • laminar
  • steady state
  • turbulent
  • quasistatic
The pressure of water in a water pipe when tap is opened and closed in respectively $$3\times 10^{5}N/m^{2}$$ and $$3.5\times 10^{5} N/m^{2}$$. Determine the velocity of flow when tap is open?
  • $$10\ m/s$$
  • $$5\ m/s$$
  • $$20\ m/s$$
  • $$15\ m/s$$
In a wind tunnel experiment, the pressures on the upper and lower surfaces of the wings are 0.90 x$$10^5$$ Pa and 0.91 x 10$$^5$$ Pa respectively. If the area of the wing is 40 m$$^2$$ the net lifting force on the wing is
  • 2 x 10$$^4$$ N
  • 4 x 10$$^4$$ N
  • 6 x 10$$^4$$ N
  • 8 x 10$$^4$$ N
Hydraulic brakes are based on
  • Pascal's law
  • Torricelli's law
  • Newton's law
  • Boyle's law
In the figure shown an ideal liquid is flowing through the tube which is of uniform area of cross-section. The liquid has velocities $$v_A$$ and $$v_B$$, and pressures $$P_A$$ and $$P_B$$ at points A and B respectively. Then it going to be

937834_c39e5e5bd8cd4c44af8c6a0f1d077ad0.png
  • $$v_B>v_A$$
  • $$v_B=v_A$$
  • $$P_B<P_A$$
  • $$P_B=P_A$$
A rain drop of radius 0.3 mm falls through air with a terminal velocity of 1 m $$s^{-1}$$. The viscosity of air is $$18 \times 10^{-5}$$ poise. The viscous force on the rain drop is then
  • $$1.018 \times 10^{-2}$$ dyne
  • $$2.018 \times 10^{-2}$$ dyne
  • $$3.018 \times 10^{-2}$$ dyne
  • $$4.018 \times 10^{-2}$$ dyne.
A steam of water flowing horizontally with a speed of $$25 ms^{-1}$$ gushes out of a tube of cross-sectional area $$10^{-3}m^2$$, and hits at a vertical wall nearby. What is the force exerted on the wall by the impact of water?
  • $$125\ N$$
  • $$625\ N$$
  • $$-650\ N$$
  • $$-1125\ N$$
Spherical balls of radius R are falling in a viscous fluid of velocity v. The retarding viscous force acting on the spherical ball is
  • directly proportional to R but inversely proportional to v.
  • directly proportional to both radius R and velocity v.
  • inversely proportional to both radius R and velocity v
  • inversely proportional to R but directly proportional to velocity v
After terminal velocity is reached, the acceleration of a body falling through a viscous fluid is
  • zero
  • equal to g
  • less than g
  • more than g
Applications of Bernoulli's theorem can be seen in the
  • dynamic lift of Aeroplane
  • hydraulic press
  • helicopter
  • none of these
Torricelli's barometer used mercury but Pascal duplicated it using French wine of density 989 kgm$$^{-3}$$. in that case, the height of the wine column for normal atmospheric pressure is (Take the density of mercury =13.6 x 10$$^3$$ kg m$$^{-3}$$)
  • 5.5 m
  • 10.5 m
  • 9.8 m
  • 15 m
The velocity of water in river is $$18 km h^{-1}$$ near the surface. If the river is 5 m deep, then the Shearing stress between the surface layer and the bottom layer is then(coefficient of viscosity of water, $$\eta = 10^{-3} Pa \,\, s$$)
  • $$10^{-2} N m^{-2}$$
  • $$10^{-3} N m^{-2}$$
  • $$10^{-4} N m^{-2}$$
  • $$10^{-5} N m^{-2}$$
A solid sphere falls with a terminal velocity v in air. If it is allowed to fall in vacuum,
  • terminal velocity of sphere = v
  • terminal velocity of sphere < v
  • terminal velocity of sphere > v
  • sphere never attains terminal velocity
A drop of water of radius 0.0015 mm is falling in air. If the coefficient of viscosity of air is $$2.0 \times 10^{-5} kg m^{-1} s^{-1}$$, the terminal velocity of the drop will be:
(The density of water = $$10^3 kg m^{-3}$$ and $$g = 10 m s^{-2}$$)
  • $$1.0 \times 10^{-4} m s^{-1}$$
  • $$2.0 \times 10^{-4} m s^{-1}$$
  • $$2.5 \times 10^{-4} m s^{-1}$$
  • $$5.0 \times 10^{-4} m s^{-1}$$
At what velocity does water emerge from an orifice in a tank in which gauge pressure is 
$$3\times 10^5N m^{-2}$$ before the flow starts? (Take the density of water= 1000 kg m$$^{-3}$$.)
  • $$24.5 m s^{-1}$$
  • $$14.5 m s^{-1}$$
  • $$34.5 m s^{-1}$$
  • $$44.5 m s^{-1}$$
Which of the following device is used to measure the rate of flow of liquid through a pipe?
  • Thermometer
  • Barometer
  • Manometer
  • Venturimeter
Two capillaries of same length and radii in the ratio 1: 2 are.connected in series. A liquid flows through them in streamlined condition. If the pressure across the two extreme ends of the combination is 1 m of water, the pressure difference across first capillary is
  • 9.4 m
  • 4.9 m
  • 0.49 m
  • 0.94 m
Which of the following diagrams does not represent a streamline flow?
A large cylindrical tank has a hole of area $$A$$ at its bottom and water is poured into the tank through a tube of cross-section area $$A$$ ejecting water at the speed $$v$$. Which of the following is true?
  • Water level in tank keeps on rising
  • No water can be stored in the tank
  • Water level will rise to height $$v^{2}/2g$$ and then stop
  • The water level will be oscillating
The velocity of the liquid coming out of a small hole of a vessel containing two different liquid of densities $$2\rho $$ and $$\rho $$ shown in the figure is
985138_4c4e8e6db829475c946cd32784376181.png
  • $$\sqrt { 6gh }$$
  • $$2\sqrt { gh }$$
  • $$2\sqrt { 2gh }$$
  • $$\sqrt { gh }$$
A tube $$1\ { cm }^{ 2 }$$ in cross section is attached to the top of a vessel $$1\ cm$$ high and of cross section $$100\ { cm }^{ 2 }$$. Water is poured into the system filling it to depth of $$100\ cm$$ above the bottom of the vessel as shown in the figure. Take $$g=10\ { m\ s }^{ -2 }$$. Find the correct statement.
985159_ee9d70478dca403ba6bc297f038f789b.png
  • The force exerted by water against the bottom of the vessel is $$100\ N$$.
  • The weight of water in the system is $$1.99\ N$$
  • Both $$(a)$$ and $$(b)$$ are correct.
  • Neither $$(a)$$ nor $$(b)$$ is correct.
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