CBSE Questions for Class 11 Engineering Physics Mechanical Properties Of Fluids Quiz 1 - MCQExams.com

The top of a water tank is open to air and its water level is maintained. It is giving out $$0.74 m^3$$ water per minute through a circular opening of 2 cm radius in its wall. The depth of the centre of the opening from the level of water in the tank is close to :
  • $$9.6 m$$
  • $$4.8 m$$
  • $$2.9 m$$
  • $$6.0 m$$
Two liquids of densities $${ \rho  }_{ 1 }$$ and $${ \rho  }_{ 2 }\left( { \rho  }_{ 2 }=2{ \rho  }_{ 1 } \right) $$ are filled up behind a square wall of side $$10m$$ as shown in figure. Each liquid has a height of $$5m$$. The ratio of the forces due to these liquids exerted on upper part $$MN$$ to that at the lower part $$NO$$ is (Assume that the liquids are not mixing)
1697241_83ebb015dad84783bb62e14f339a6b46.png
  • $$1/4$$
  • $$2/3$$
  • $$1/2$$
  • $$1/3$$
A capillary tube (A) is dipped in water. Another identical tube (B) is dipped in a soap-water solution. Which of the following shows the relative nature of the liquid columns in the two tubes? 
A glass capillary tube is of the shape of truncated cone with an apex angle $$\alpha$$ so that its two ends have cross sections of different radii. When dipped in water vertically, water rises in it to a height $$h$$, where the radius of its cross section is $$b$$. If the surface tension of water is $$S$$, its density is $$\rho$$, and its contact angle with glass is $$\theta$$, the value of $$h$$ will be ($$g$$ is the acceleration due to gravity)
113880.jpg
  • $$\dfrac{2S}{b \rho g} \cos (\theta - \alpha )$$
  • $$\dfrac{2S}{b \rho g} \cos (\theta+ \alpha )$$
  • $$\dfrac{2S}{b \rho g} \cos (\theta - \alpha /2)$$
  • $$\dfrac{2S}{b \rho g} \cos (\theta + \alpha /2)$$
If the density of air is $$\rho_a$$ and that of the liquid $$\rho_l$$, then for a given piston speed the rate (volume per unit time) at which the liquid is sprayed will be proportional to
113915.jpg
  • $$\displaystyle \sqrt{\dfrac{\rho_a}{\rho_l}}$$
  • $$\sqrt{\rho_a \rho_l}$$
  • $$\displaystyle \sqrt{\dfrac{\rho_l}{\rho_a}}$$
  • $$\rho_l$$
A person in a lift is holding a water jar, which has a small hole at the lower end of its side. When the lift is at rest, the water jet coming out of the hole hits the floor of the lift at a distance $$d$$ of $$1.2 m$$ from the person. In the following, state of the lift's motion is given in List I and the distance where the water jet hits the floor of the lift is given in List II. Match the statements from List I with those in List II and select the correct answer using the code given below the lists.
List IList II
P.Lift is accelerating vertically up.1.$$d= 1.2 m$$
Q.Lift is accelerating vertically down with an acceleration less than the gravitational acceleration.2.$$d > 1.2 m$$
R.Lift is moving vertically up with constant speed.3.$$d < 1.2 m$$
S.Lift is falling freely.4.No water leaks out of the jar
  • P-2, Q-3, R-2, S-4
  • P-2, Q-3, R-1, S-4
  • P-1, Q-1, R-1, S-4
  • P-2, Q-3, R-1, S-1
A wind with speed $$40$$ m/s blows parallel to the roof of a house. The area of the roof is $$250\ m^2$$. Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be $$(\rho_{air}=1.2 \ kg/m^3)$$
  • $$2.4\times 10^5N$$, upward
  • $$2.4\times 10^5N$$, downward
  • $$4.8\times 10^5N$$, downward
  • $$4.8\times 10^5N$$, upward
A small hole of an area of cross-section $$2 mm^2$$ is present near the bottom of a fully filled open tank of height 2 m. Taking $$g = 10 m/s^2$$,  the rate of flow of water through the open hole would be nearly 
  • $$12.6 \times 10^{-6} m^3/s$$
  • $$8.9 \times 10^{-6} m^3/s$$
  • $$2.23 \times 10^{-6} m^3/s$$
  • $$6.4 \times 10^{-6} m^3/s$$
  • Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
  • Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
  • Assertion is correct but Reason is incorrect.
  • Both Assertion and Reason are incorrect.
A spherical body of diameter D is falling in viscous medium. Its terminal velocity is proportional to:
  • $${ V }_{ 1 }\propto { D }^{ 1/2 }$$
  • $${ V }_{ 1 }\propto { D }^{ 3/2 }$$
  • $${ V }_{ 1 }\propto { D }^{ 2 }$$
  • $${ V }_{ 1 }\propto { D }^{ 5/2 }$$
The velocity of efflux of a liquid through an orifice in the bottom of the tank does not depend upon:
  • size of orifice
  • height of liquid
  • acceleration due to gravity
  • density of liquid
What is a pressure on the smaller piston if both the pistons are at same horizontal level? (Take $$g=10 ms^{-2})$$
  • 3 Pa
  • $$4\times 10^3 Pa$$
  • $$6\times 10^5 Pa$$
  • 1000 Pa
In turbulent flow, the velocity of the liquid molecules in contact with the walls of the tube.
  • is zero
  • is maximum
  • is equal to critical velocity
  • may have any value
Which of the following works on Pascal's law?
  • Sprayer
  • Venturimeter
  • Hydraulic lift
  • Aneroid barometer
The volume of liquid flowing per second out of an orifice at the bottom of the tank does not depend upon:
  • the density of the liquid
  • acceleration due to gravity
  • the height of the liquid above orifice
  • the area of the orifice
Stream line motion becomes turbulent motion when the velocity of the liquid is:
  • beyond critical velocity
  • critical velocity
  • below critical velocity
  • variable velocity
Which of the following is a characteristic of turbulent flow?
  • velocity more than critical velocity
  • irregular flow
  • molecules crossing from one layer to the other
  • All of the above
In a laminar flow at a given point the magnitude and direction of the velocity of the fluid:
  • both are constant
  • magnitude is only constant
  • direction is only constant
  • both are not constant
The terminal velocity depends upon:
  • $$ \dfrac {1}{r}$$
  • $$ \dfrac {1}{r^2}$$
  • $$ \dfrac {1}{r^3}$$
  • $$r^2$$
The correct formula of critical velocity $$\left(V_c \right)$$ is :
  • $$V_c = \displaystyle \dfrac {k \eta d}{r}$$
  • $$V_c = \displaystyle \dfrac {k \eta}{dr}$$
  • $$V_c = \displaystyle \dfrac {dr}{k \eta}$$
  • $$V_c = \displaystyle \dfrac {r \eta}{dk}$$
The velocity efflux of a liquid is:
  • $$\sqrt {2 gh}$$
  • $$2 gh$$
  • $$gh$$
  • $$\sqrt {g h}$$
A raindrop falls near the surface of the earth with almost uniform velocity because:
  • its weight is negligible.
  • the force of surface tension balances its weight.
  • the force of viscosity of air balances its weight.
  • the drops are charged and atmospheric electric field balances its weight.
When a sphere falling in a viscous fluid attains a terminal velocity, then:
  • the net force acting on the sphere is zero
  • the drag force balances the buoyant force
  • the drag force balances the weight of the sphere
  • the buoyant force balances the weight and drag force
In a stream line (laminar flow) the velocity of flow at any point in the liquid:
  • does not vary with time
  • may vary in direction but not in magnitude
  • may vary in magnitude but not in direction
  • may vary both in magnitude and direction
The velocity of a liquid coming out of a hole in the tank wall is:
  • more if the hole is near the upper end.
  • more if the hole is at the centre of the wall.
  • more if hole is near the bottom.
  • velocity of flow does not depend upon the position of the hole.
State whether true or false:
The deeper an underwater swimmer goes, the more strongly the water pushes on his body and the greater is the pressure that he experiences.
  • True
  • False
Choose the correct answer from the given options below:
The meniscus formed by water in a test tube is of --------- shape.
  • horizontal
  • triangular
  • concave
  • convex
Name the kind of meniscus formed in case of water.
  • Concave
  • Convex
  • Both A & B
  • None
If a capillary tube is tilted to $$45^{\circ}$$ and $$60^{\circ}$$ from the vertical then the ratio of length $$l_{1}$$ and $$l_{2}$$ of liquid columns  in it will be -
  • $$1: \sqrt{2}$$
  • $$\sqrt{2}:1$$
  • 1:2
  • 2:1
If a wax coated capillary tube is dipped in water, then water in it will-
  • rise up
  • depress
  • sometimes rise and sometimes fall
  • rise up and come out as a fountain
Shape of meniscus for a liquid of zero angle of contact is convex.
  • True
  • False
Answer true or false. 'Faster the movement of the air greater is the drop in pressure'.
  • True
  • False
A pilot wants to fly his aeroplane in atmosphere free space 
  • He cannot do it
  • He can do it easily
  • He can do it but with difficulty
  • None of these
The height of mercury which exerts the same pressure as 20 cm of a water column, is equal to
  • $$1.48$$ cm
  • $$14.8$$ cm
  • $$148$$ cm
  • none of these
Curve in the upper surface of a liquid to the surface of the container is known as
  • Surface teusion
  • Meniscus
  • Both
  • Elasticity
If the meniscus of a liquid is concave in shape, then
  • force of adhesion > force of cohesion
  • force of adhesion = force of cohesion
  • force of adhesion < force of cohesion
  • None of the above
In steady horizontal flow:
  • the pressure is greatest where the speed is leas
  • the pressure is independent of speed
  • the pressure is least where the speed is least
  • (a) and (c) are correct
In a turbulent flow, the velocity of the liquid molecules in contact with the walls of the tube is :
  • Zero
  • Maximum
  • Equal to critical velocity
  • May have any value
The horizontal flow of fluid depends upon 
  • Pressure difference
  • Amount of fluid
  • Density of fluid
  • All the above
Pressure (P) exented by liquid on walls of the container when h = height of the liquid column, f = density, g is acceleration due to gravity
  • $$p = h f g$$
  • $$p = \dfrac{df}{g}$$
  • $$p = \dfrac{hg}{f}$$
  • $$p = \dfrac{df}{h}$$
The SI unit of hydro-static pressure is :
  • Pa
  • $$ Nm^{-1}$$
  • Nm
  • $$kg$$ $$wt$$ $$m^{-2}$$
Bernoulli's equation is applicable to points :
  • In a steadily flowing liquid
  • In a stream line
  • In a straight line perpendicular to a stream line
  • For ideal liquid stream line flow on a stream line
 1 mm Hg is equal to
  • 1 atm
  • 1.013 $$\times$$10$$^5$$ Pa
  • 133.29 atm
  • 1.316 $$\times$$10$$^{-3}$$ atm
If a liquid does not wet glass, its angle of contact is:
  • Zero
  • Acute
  • Obtuse
  • Right angle
If the surface tension of water is $$0.06N/m$$, then the capillary rise in a tube of a diameter $$1mm$$ is :($$\theta={0}^{o}$$)
  • $$1.22cm$$
  • $$2.44cm$$
  • $$3.12cm$$
  • $$3.86cm$$
The ordinary pressure of air surrounding us is
  • 15 pounds
  • 16 pounds
  • 14.2 pounds
  • 14.7 pounds
When a plane moves along the runway, the air above the wing speeds up more, So the pressure
  • Lowers
  • Increases
  • Raises
  • No Pressure
Choose the correct option. Consider tube to be made of glass.
455404.png
  • A: water

    B: mercury
  • A: mercury

    B: water
  • A: hot water

    B: cold water
  • A: hot mercury

    B: cold mercury
Choose the correct statement among the following
  • The upper surface of a stationary liquid is always horizontal.
  • The pressure of a given liquid is directly proportional to the depth of the liquid.
  • Pressure at a given depth inside a stationary liquid is different at all points on the horizontal plane.
  • Both (A) and (B)
Vacuum above the mercury level in a barometer is called:
  • Torricelli vacuum
  • Archimedes vacuum
  • newtons vacuum
  • Pascal vacuum
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