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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 0.74m3 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 :
  • 9.6m
  • 4.8m
  • 2.9m
  • 6.0m
Two liquids of densities ρ1 and ρ2(ρ2=2ρ1) 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 α 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 ρ, and its contact angle with glass is θ, the value of h will be (g is the acceleration due to gravity)
113880.jpg
  • 2Sbρgcos(θα)
  • 2Sbρgcos(θ+α)
  • 2Sbρgcos(θα/2)
  • 2Sbρgcos(θ+α/2)
If the density of air is ρa and that of the liquid ρl, then for a given piston speed the rate (volume per unit time) at which the liquid is sprayed will be proportional to
113915.jpg
  • ρaρl
  • ρaρl
  • ρlρa
  • ρl
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 \times10^5 Pa
  • 133.29 atm
  • 1.316 \times10^{-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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