CBSE Class 11 Fluid Flow Worksheet A

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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

Answer: A

Question. A boat having a length of 3 metres and breadth 2 metres is floating on a lake. The boat sinks by one cm when a man gets on it. The mass of the man is
(a) 60 kg
(b) 62 kg
(c) 72 kg
(d) 128 kg

Answer: A

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

Answer: D

Question. A beaker containing a liquid of density ρ moves up with an acceleration a. The pressure due to the liquid at a depth h below the free surface of the liquid is
(a) h ρ g
(b) h ρ (g – a)
(c) h ρ (g + a)
(d) 2h h ρ(g+a/g-a)

Answer: C

Question. Two vessels A and B of cross-sections as shown in figure contain a liquid up to the same height. As the temperature rises, the liquid pressure at the bottom (neglecting expansion of the vessels) will 

(a) increase in A, decrease in B
(b) increase in B, decrease in A
(c) increase in both A and B
(d) decrease in both A and B

Answer: 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

Answer: B

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

Answer: 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

Answer: 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

Answer: A

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

Answer: B

Question. Two soap bubbles (surface tension T) coalesce to form a big bubble under isothermal condition. If in this process the change in volume be V and the surface area be S, then the correct relation is (P is atmospheric pressure)
(a) PV + TS = 0
(b) 3PV + 4TS = 0
(c) 3PV + TS = 0
(d) 4PV + 3TS = 0

Answer: B

Question. Surface tension may be defined as
(a) the work done per unit area in increasing the surface area of a liquid under isothermal condition
(b) the work done per unit area in increasing the surface area of a liquid under the adiabatic condition
(c) the work done per unit area in increasing the surface area of liquid under both isothermal and adiabatic condition
(d) free surface energy per unit volume

Answer: A

Question. The density of ice is x gram/litre and that of water is y gram/ litre. What is the change in volume when m gram of ice melts?
(a) mx y (x – y)
(b) m/(y – x)
(c) m(1/y - 1/x)
(d) (y – x)/x

Answer: C

Question. An ice-berg floating partly immersed in sea water of density 1.03 g/cm³. The density of ice is 0.92 g/cm³. The fraction of the total volume of the iceberg above the level of sea water is
(a) 8.1%
(b) 11%
(c) 34%
(d) 0.8%

Answer: B

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

Answer: A

Question. The rain drops falling from the sky neither injure us nor make holes on the ground because they move with
(a) constant acceleration
(b) variable acceleration
(c) variable speed
(d) constant terminal velocity

Answer: 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)

Answer: A

Question. A cylinder is filled with non-viscous liquid of density d to a height h₀ and a hole is made at a height h₁ from the bottom of the cylinder. The velocity of the liquid issuing out of the hole is
(a) √2gh₀
(b) √2g (h₀ - h₁)
(c) √dgh₁
(d) √dgh₀

Answer: 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

Answer: B

Question. Figure here shows the vertical cross section of a vessel filled with a liquid of density r. The normal thrust per unit area on the walls of the vessel at the point P, as shown, will be 

(a) hrg
(b) Hrg
(c) (H – h) ρg
(d) (H – h) ρg cosθ

Answer: C

1.What is conserved in Bernoulli’s theorem?

2. If the rate of flow of liquid through a horizontal pipe of length l and radius R is Q.

What is rate of flow of liquid if length and radius of tube is doubled?

3. Water is coming out of a hole made in the wall of tank filled with fresh water. If the size of the hole is increased, will the velocity of efflux change?

4. The accumulation of snow on an aero plane wing may reduce the lift. Explain? 

5. Two pipes P and Q having diameters 2 × 10^-2 m and 4 × 10^-2 m respectively are joined in Series with the main supply line of water. What is the velocity of water flowing in pipe P?

6. A horizontal pipe of diameter 20 cm has a constriction of diameter 4 cm. The velocity of water in the pipe is 2m/s and pressure is 10 N/m². Calculate the velocity and pressure at the constriction?

7. The reading of a pressure metre attached to a closed is 2.5 × 10⁵ N/m². On opening the valve of pipe, the reading of the pressure metre reduces to 2.0 × 10⁵ N/m². Calculate the speed of water flowing through the pipe?

8. A large bottle is fitted with a siphon made of capillary glass tubing. Compare the Co-efficient of viscosity of water and petrol if the time taken to empty the bottle in the two cases is in the ratio 2:5. Given specific gravity of petrol = 0.8

9. Under a pressure head, the rate of flow of liquid through a pipe is Q. If the length of pipe is doubled and diameter of pipe is halved, what is the new rate of flow?

10. In a horizontal pipeline of uniform area of cross – section, the pressure falls by 5 N/m² between two points separated by a distance of 1 Km. What is the change in kinetic energy per Kg of oil flowing at these points? Given Density of oil = 800 Kg/m³?

11. 1) Water flows steadily along a horizontal pipe at a rate of 8 × 10^-3m³/s. If the area of cross – section of the pipe is 40 × 10^-4 m2, Calculate the flow velocity of water.

2) Find the total pressure in the pipe if the static pressure in the horizontal pipe is 3 × 10⁴ Pa. Density of water is 1000 Kg/m³.

3. What is the net flow velocity if the total pressure is 3.6 × 10⁴ Pa? 

Click on link below to download CBSE Class 11 Fluid Flow Worksheet A.