# MCQ Questions For Class 11 Physics Chapter 10 Mechanical Properties of Fluids

Students can refer to the following MCQ on Mechanical Properties of Fluids class 11 PDF with Answers provided below based on the latest curriculum and examination pattern issued by CBSE and NCERT. Our teachers have provided here a collection of multiple-choice questions for Chapter 10 Mechanical Properties of Fluids Class 11 Physics covering all topics in your textbook so that students can assess themselves on all important topics and thoroughly prepare for their exams

## MCQ on Mechanical Properties of Fluids class 11 PDF with Answers

We have provided below MCQ on Mechanical Properties of Fluids class 11 PDF with answers which will help the students to go through the entire syllabus and practice multiple choice questions provided here with solutions. As MCQ Questions for Class 11 Physics pdf download can be really scoring for students, you should go through all problems provided below so that you are able to get more marks in your exams.

Question. Two non-mixing liquids of densities r and nr (n > 1) are put in a container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL (p < 1) in the denser liquid. The density d is equal to
(a) {2 + (n – 1)p}r
(b) {1 + (n – 1)p}r
(c) {1 + (n + 1)p}r
(d) {2 + (n + 1)p}r

B

Question. The cylindrical tube of a spray pump has radius R, one end of which has n fine holes, each of radius r. If the speed of the liquid in the tube is V, the speed of the ejection of the liquid through the holes is
(a) VR2 /n3r2
(b) VR2 /nr
(c) VR/n2r2
(d) VR/nr

D

Question. A small hole of area of cross-section 2 mm2 is present near the bottom of a fully filled open tank of height 2 m. Taking g = 10 m/s2, the rate of flow of water through the open hole would be nearly
(a) 6.4 × 10–6 m3/s
(b) 12.6 × 10–6 m3/s
(c) 8.9 × 10–6 m3/s
(d) 2.23 × 10–6 m3/s

B

Question. A wind with speed 40 m/s blows parallel to the roof of a house. The area of the roof is 250 m2. 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 (rair = 1.2 kg/m3)
(a) 2.4 × 105 N, upwards
(b) 2.4 × 105 N, downwards
(c) 4.8 × 105 N, downwards
(d) 4.8 × 105 N, upwards

A

Question. A fluid is in streamline flow across a horizontal pipe of variable area of cross section. For this which of the following statements is correct?
(a) The velocity is maximum at the narrowest part of the pipe and pressure is maximum at the widest part of the pipe.
(b) Velocity and pressure both are maximum at the narrowest part of the pipe.
(c) Velocity and pressure both are maximum at the widest part of the pipe.
(d) The velocity is minimum at the narrowest part of the pipe and the pressure is minimum at the widest part of the pipe.

A

Question. Two small spherical metal balls, having equal masses, are made from materials of densities r1 and r2(r1= 8r2) and have radii of 1mm and 2 mm, respectively. They are made to fall vertically (from rest) in a viscous medium whose coefficient of viscosity equals h and whose density is 0.1 r2. The ratio of their terminal velocities would be
(a) 79/72
(b) 19/36
(c) 39/72
(d) 79/36

D

Question. A small sphere of radius ‘r’ falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to
(a) r3
(b) r2
(c) r5
(d) r4

C

Question. A capillary tube of radius r is immersed in water and water rises in it to a height h. The mass of the water in the capillary is 5 g. Another capillary tube of radius 2r is immersed in water. The mass of water that will rise in this tube is
(a) 2.5 g
(b) 5.0 g
(c) 10.0 g
(d) 20.0 g

C

Question. A soap bubble, having radius of 1 mm, is blown from a detergent solution having a surface tension of 2.5 × 10–2 N/m. The pressure inside the bubble equals at a point Z0 below the free surface of water in a container. Taking g = 10 m/s2, density of water = 103 kg/m3, the value of Z0 is
(a) 0.5 cm
(b) 100 cm
(c) 10 cm
(d) 1 cm

D

Question. The excess pressure inside the first soap bubble is three times that inside the second bubble then, the ratio of volume of the first to the second bubble will be :
(a) 1 : 27
(b) 3 : 1
(c) 1 : 3
(d) 1 : 9

A

Question. Two small drops of mercury, each of radius R coalesce to form a single large drop. The radio of the total surface energies before and after the change is :
(a) 1 : 21/3
(b) 21/3 : 1
(c) 2 : 1
(d) 1 : 2

B

Question. The lift of an air plane is based on
(a) Torricelli’s theorem
(b) Bernoulli’s theorem
(c) Law of gravitation
(d) Conservation of linear momentum

B

Question. A ring is cut from a platinum tube 8.5 cm internal and 8.7 cm external diameter. It is supported horizontally from the pan of a balance, so that it comes in contact with the water in a glass vessel.
If an extra 3.97. If is required to pull it away from water, the surface tension of water is
(a) 72 dyne cm–1
(b) 70.80 dyne cm–1
(c) 63.35 dyne cm–1
(d) 60 dyne cm–1

A

Question. A water tank of height 10m, completely filled with water is placed on a level ground. It has two holes one at 3 m and the other at 7 m from its base. The water ejecting from
(a) both the holes will fall at the same spot
(b) upper hole will fall farther than that from the lower hole
(c) upper hole will fall closer than that from the lower hole

A

Question. A rectangular film of liquid is extended from (4 cm × 2 cm) to (5 cm × 4 cm). If the work done  is 3 × 10–4 J, the value of the surface tension of the liquid is
(a) 0.250 N m–1
(b) 0.125 N m–1
(c) 0.2 N m–1
(d) 8.0 N m–1

B

Question. Three liquids of densities r1, r2 and r3 (with r1 > r2 > r3), having the same value of surface tension T, rise to the same height in three identical capillaries. The angles of contact q1, q2 and q3 obey
(a) p/2 > q1 > q2>q3 ≥ 0
(b) 0 ≤ q1 < q2 < q3 < p/2
(c) p/2 < q1 < q2 < q3 < p
(d) p > q1 > q2 > q3 > p/2

B

Question. Water rises to a height h in capillary tube. If the length of capillary tube above the surface of water is made less than h, then
(a) water rises upto a point a little below the top and stays there
(b) water does not rise at all
(c) water rises upto the tip of capillary tube and then starts overflowing like a fountain
(d) water rises upto the top of capillary tube and stays there without overflowing.

D

Question. Iceberg floats in sea water with a part of it submerged. The percentage fraction of the ice berg above sea is (Density of ice = 0.9 g cm–3, density of sea water = 1.1 g cm–3)
(a) 18%
(b) 12%
(c) 10%
(d) 8%

A

Question. A tall cylinder is filled with viscous oil. A round pebble is dropped from the top with zero initial velocity. From the plots shown, indicate the one that represents the velocity (v) of the pebble as a function of time (t).

C

Question. Along a streamline
(a) the velocity of a fluid particle remains constant
(b) the velocity of all fluid particles crossing a given position is constant.
(c) the velocity of all fluid particles at a given instant is constant.
(d) the speed of a fluid particle remains constant.

B

Question. A plane is in level fight at constant speed and each of its two wings has an area of 25 m2. If the speed of the air on the upper and lower surfaces of the wing are 270 km h–1 and 234 km h–1 respectively, then the mass of the plane is (Take the density of the air = 1 kg m–3)
(a) 1550 kg
(b) 1750 kg
(c) 3500 kg
(d) 3200 kg

C

Question. A metal block of area 0.10 m2 is connected to a 0.010 kg mass via a string that passes over an ideal pulley (considered massless and frictionless) as shown in figure. A liquid with a film thickness of 0.30 mm is placed between the block and the table. When released the block moves to the right with a constant speed of 0.085 m s–1. The coefficient of viscosity of the liquid is (Take g = 9.8 m s–2) Film 0.01 kg

(a) 2.45 × 10–3 Pa s
(b) 3.45 × 10–3 Pa s
(c) 6.45 × 10–3 Pa s
(d) 7.45 × 10–3 Pa s

B

Question. Which of the following statements is incorrect?
(a) Blood is more viscous than water.
(b) The blood pressure in humans is greater at the feet than at the brain.
(c) The angle of contact of mercury with glass is obtuse while that of water with glass is acute.
(d) A spinning cricket ball in air follows a parabolic trajectory.

D

Question. 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
(a) 30 N
(b) 60 N
(c) 90 N
(d) 100 N

C

Question. Equal volume of two immiscible liquids of densities p and 2p 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 v1 and v2 are the velocities of efflux at these two holes, thenv1/v2

a) 1/2√2
b) 1/2
c) 1/4
d) 1/√2

D

Question. The two femurs each of cross-sectional area 10 cm2 support the upper part of a human body of mass 40 kg. The average pressure sustained by the femurs is (Take g = 10 m s–2)
(a) 2 × 103 N m–2
(b) 2 × 104 N m–2
(c) 2 × 105 N m–2
(d) 2 × 106 N m–2

C

Question. The surface tension of soap solution at a temperature 20°C is 2.5 × 10–2 N m–1. The excess pressure inside a bubble of soap solution of radius 6 mm is
(a) 12.5 Pa
(b) 14.2 Pa
(c) 15.5 Pa
(d) 16.7 Pa

D

Question. The water flows from a tap of diameter 1.25 cm with a rate of 5 × 10–5 m3 s–1. The density and coefficient of viscosity of water are 103 kg m–3 and 10–3 Pa s respectively. The flow of water is
(a) steady with Reynolds number 5100
(b) turbulent with Reynolds number 5100
(c) steady with Reynolds number 3900
(d) turbulent with Reynolds number 3900

B

Question. The excess pressure inside a spherical drop of water is four times that of another drop. Then their respective mass ratio is
(a) 1 : 16
(b) 8 : 1
(c) 1 : 4
(d) 1 : 64

D

Question. An ideal fluid flows through a pipe of circular cross-section made of two sections with  diameters 2.5 cm and 3.75 cm. The ratio of the velocities in the two pipes is
(a) 9 : 4
(b) 3 : 2
(c) √3 : √2
(d) √2 : √3

A

Question. In the figure, the velocity v3 will be

(a) zero
(b) 4 m s–1
(c) 1 m s–1
(d) 3 m s–1

C

Question. The flow rate of water from a tap of diameter 1.25 cm is 3 L per min. The coefficient of viscosity of water is 10–3 Pa s. The nature of the flow is Mechanical Properties of Fluids 25
(b) Turbulent
(c) Laminar
(d) None of these

B

Question. The angle of contact at the interface of waterglass is 0°, Ethylalcohol-glass is 0°, mercuryglass is 140° and Methyliodide-glass is 30°. A glass capillary is put in a trough containing one of these four liquids. It is observed that the meniscus is convex. The liquid in the trough is
(a) water
(b) ethylalcohol
(c) mercury
(d) methyliodide.

C

Question. Which of the following figure shown below is correct regarding the steady flow of a non viscous liquid?

A

Question. Water is flowing in a river. If the velocity of a layer at a distance 10 cm from the bottom is 20 cm/s, the velocity of layer at a height of 40 cm from the bottom is
(a) 10 cm/s
(b) 20 cm/s
(c) 30 cm/s
(d) 80 cm/s

D

Question. A U tube contains water and methylated spirit separated by mercury. The mercury columns in the two arms are at the same level with 10 cm of water in one arm and 12.5 cm of spirit in the other as shown in figure.

The relative density of the spirit is
(a) 0.6
(b) 0.8
(c) 1.0
(d) 1.25

B

Question. A cylindrical vessel is filled with water up to height H. A hole is bored in the wall at a depth h from the free surface of water. For maximum range, h is equal to
(a) H/4
(b) H/2
(c) 3H/4
(d) H

B

Question. The terminal speed of a sphere of gold (density = 19.5 kg m–3) is 0.2 m s–1 in a viscous liquid (density = 1.5 kg m–3). Then the terminal speed of a sphere of silver (density = 10.5 kg m–3) of the same size in the same liquid is
(a) 0.1 m s–1
(b) 0.4 m s–1
(c) 0.2 m s–1
(d) 0.3 m s–1

A

Question. Which of the following diagrams does not represent a streamline flow?

D

Question. The rate of flow of a liquid through a capillary tube of radius r is V when the pressure difference across the two ends of the capillary is P. If pressure is increased by 3P and radius is reduced to r/2 , then the rate of flow becomes
(a) V/8
(b) V/4
(c) V/2
(d) V/9

B

Question. An aircraft of mass 4 × 105 kg with total wing area 500 m2 in level flight at a speed of 720 km h–1. The density of air at its height is 1.2 kg m–3. The fractional increase in the speed of the air on the upper surface of its wings relative to the lower surface is (Take g = 10 m s–2)
(a) 0.04
(b) 0.08
(c) 0.17
(d) 0.34

C

Question. In old age arteries carrying blood in the human body become narrow resulting in an increase in the blood pressure. This follows from
(a) Pascal’s law
(b) Stokes’ law
(c) Bernoulli’s principle
(d) Archimede’s principle

C

Question. The wettability of a surface by a liquid depends primarily on
(a) density
(b) angle of contact between the surface and the liquid
(c) viscosity
(d) surface tension.

B

Question. A small ball (menu) falling under graivty in a viscous medium experiences a drag force proportional to the instantaneous speed u such that Fdrag = Ku . Then the terminal speed of the ball within the viscous medium is
(a) K/mg
(b) mg/K
(c) √mg?k
(d) (mg/K)2

A

Question. The constant velocity attained by a body while falling through a viscous medium is termed as
(a) critical velocity
(b) terminal velocity
(c) threshold velocity
(d) None of these

B

Question. The difference between viscosity and solid friction is/are
(a) viscosity depends on area while solid friction does not
(b) viscosity depends on nature of material but solid friction does not
(c) both (a) and (b)
(d) neither (a) nor (b)

A

Question. Water is not used in thermometer because
(a) it sticks to glass
(b) its shows anamalous expansion
(c) both (a) and (b)
(d) neither (a) nor (b)

C

Question. Toricelli’s theorem is used to find
(a) the velocity of efflux through an orifice.
(b) the velocity of flow of liquid through a pipe.
(c) terminal velocity
(d) critical velocity

A

Question. Gases do not posses
(a) density
(b) surface tension
(c) volume
(d) viscosity

B

Question. Paint-gun is based on
(a) Bernoulli’s theorem
(b) Archimedes’ principle
(c) Boyle’s law
(d) Pascal’s law

A

Question. Water is flowing through a horizontal pipe having a restriction, then
(a) pressure will be greater at the restriction.
(b) pressure will be greater in the wider portion.
(c) pressure will be same throughout the length of the pipe.
(d) None of these

B

Question. Fevicol is added to paint to be painted on the walls, because
(a) it increases adhesive force between paint and wall.
(b) it decreases adhesive force between paint and wall molecules.
(c) it decreases cohesive force between paint molecules.
(d) None of these

A

Question. Consider a 1 c.c. sample of air at absolute temperature T0 at sea level and another 1 c.c. sample of air at a height where the pressure is one-third atmosphere. The absolute temperature T of the sample at the height is
(a) equal to T0/3
(b) equal to 3/T0
(c) equal to T0

A

Question. The terminal velocity depends upon
(a) 1/r
(b) 1/r2
(c ) 1/r3
(d) r2

D

Question. The velocity of efflux of a liquid through an orifice in the bottom of the tank does not depend upon
(a) size of orifice
(b) height of liquid
(c) acceleration due to gravity
(d) density of liquid

A

Question. At the boiling point of a liquid, surface tension
(a) is zero
(b) is infinite
(c) is same as that at any other temperature
(d) cannot be determined

A

Question. The surface energy of a liquid drop of radius r is proportional to
(a) r3
(b) r2
(c) r
(d) 1/r

B

Question. A liquid is contained in a vessel. The liquid-solid adhesive force is very weak as compared to the cohesive force in the liquid. The shape of the liquid surface will be
(a) horizontal
(b) vertical
(c) concave
(d) convex

D

Question. Two liquids drops coalesce to form a large drop. Now,
(a) energy is liberated
(b) energy is neither liberated nor absorbed
(c) some mass gets converted into energy
(d) energy is absorbed

A

Question. A man is sitting in a boat which is floating in pond. If the man drinks some water from the pond, the level of water in the pond will
(a) rise a little
(b) fall a little
(c) remain stationary
(d) none of these