06 Fluid Dynamics Premium VersionBy Bomvirtual.com / June 11, 2025 0% 0 votes, 0 avg 57 12345678910111213141516171819202122232425262728293031323334353637383940414243444546 Created by Bomvirtual.com 06 Fluid Dynamics Premium Version 1 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 1) Water enters through end A with speed v₁ and leaves through end B with speed v₂ of a cylindrical tube AB. The tube is always completely filled with water. In case I, the tube is horizontal; in case II, it is vertical with end A upwards; and in case III, it is vertical with end B upwards. We have v₁ = v₂ for A) Case I B) Case II C) Each case D) Case III This happens in accordance with equation of continuity and this equation was derived on the principle of conservation of mass and it is true in every case, either tube remain horizontal or vertical. 2 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 2) One end of a cylindrical pipe has a radius of 1.5cm. Water (density = 1.0 × 10³ kg/m³) is leaving the pipe. The mass flow rate is: ETEA 2016 A) 4.9kg/s B) 2.5kg/s C) 7.0 × 10³ kg/s D) 48 kg/s Mass flow rate=ρQ=(1000)(4.9×10 −3 )=4.9kg/s 3 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 3) An application of Bernoulli’s equation for fluid flow is found in A) Viscosity meter B) Hydraulic press C) Dynamic lift of an aeroplane D) Capillary rise Bernoulli’s principle explains lift: Faster airflow over the curved upper wing surface creates lower pressure, lifting the plane. 4 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Fluid Flow 4) S.I. unit of the rate of flow of a fluid: NUMS-2018 A) meter/sec B) meter²/sec C) meter²/sec² D) meter³/sec The rate of flow (volume flow rate, Q) is the volume of fluid passing per unit time. Its SI unit is cubic meters per second (m³/s). 5 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 5) Two meter high tank is full of water. A hole is made in the middle of the tank. The speed of efflux is; ETEA-2019+2011 A) 9.8 m/s B) 3.75 m/s C) 4.9 m/s D) 4.42 m/s v= √2gh=√(2 x9.8×1)=√19.8 = 4.4 m/s 6 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 6) The working of carburetor of a car uses A) gravitational law B) equation of continuity C) stoke’s theorem D) Bernoulli’s theorem A carburetor relies on Bernoulli’s principle: air flows faster through a narrow section (venturi), creating a pressure drop that draws fuel into the airstream. 7 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 7) In fluid flow, for the equation of continuity A₁v₁ = A₂v₂, if the velocity of the fluid at one end is doubled, then what will be the cross-sectional area at this end? MDCAT-2015 A) (Double)² B) Double C) Half D) (Half)² A α 1/v, The area halves when velocity doubles. 8 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 8) The equation of continuity can be derived from: ETEA-2019 A) Law of conservation of momentum B) Law of conservation of charge C) Law of conservation of energy D) Law of conservation of mass The equation of continuity can be derived from Law of conservation of mass 9 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 9) According to the equation of continuity A₁V₁ = A₂V₂ = constant. The constant is equal to A) density of fluid B) flow rate C) volume of fluid D) mass of fluid The product Av is the volume flow rate (Q), which remains constant for incompressible flow. 10 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 10) The venturi’s relation is given by A) P₁ + P₂ = ρv₂² B) P₁ – P₂ = ρv₂² C) P₁ + P₂ = 1/2 ρv₂² D) P₁ – P₂ = 1/2 ρv₂² In a Venturi meter, the pressure difference (P1−P2 ) between two points is related to the fluid’s kinetic energy per unit volume: P₁ – P₂ = 1/2 ρv₂² 11 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Fluid Flow 11) If each particle of fluid is passing through the same point, what would be the flow? NUMS-2016 A) Streamline B) Tubular C) Both A and B D) Linear Streamline flow (laminar flow) occurs when fluid particles follow smooth paths (streamlines) and do not cross each other. If all particles pass through the same point, it implies streamlined motion. 12 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 12) The equation of continuity for fluid flow can be derived from the conservation of: ETEA 2015 A) Mass B) Volume C) Pressure D) Energy From the ceonservation of mass, equation of continuity can be derived m = m →rV= rV → rAx=rAx → rAvt = rAvt → Av =Av 13 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 13) Bernoulli’s equation can be derived from the conservation of: ETEA 2015 A) Volume B) Mass C) Pressure D) Energy Work = K.E + P/E, it is the first ste in derivation of bernouli equation, so Bernoulli’s equation can be derived from the conservation of: energy. 14 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 14) A rectangular vessel when full of water takes 10 minutes to be emptied through an orifice in its bottom. How much time will it take to be emptied when half filled with water A) 7 minute B) 3 minute C) 9 minute D) 5 minute Time taken to be emptied for h height, t = √(2h/g) and for h/2 height, t’ = √((2h/2)/g) = √(h/g) ∴t’/t=1/√2=>t’=1/√2=10/√2=7 minute 15 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 15) The Torricelli’s expression is expressed as A) v₂ = √((h₁+h₂)/2g) B) v₂ = √(2g(h₁+h₂)) C) v₂ = √(2g/(h₁+h₂)) D) v₂ = √(2g(h₁-h₂)) Torricelli’s theorem gives the speed of efflux (v2) of a fluid under gravity from an orifice at depth h=h1−h2 in a tank: v2 = √(2g(h₁-h₂ )) 16 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 16) An incompressible liquid flows along a pipe with areas of cross-section A₁ and A₂ with velocities V₁ and V₂ respectively. The ratio of the speeds V₁/V₂ is: ETEA 2015 A) A₁/A₂ B) A₂/A₁ C) √(A₂/A₁) D) √(A₁/A₂) It is aquation of continuity; As; A1 V1= A2 V2 and V1 / V2 = A2 / A1 17 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 17) In Bernoulli’s equation the term 1/2 ρv² is called: MDCAT-2016 A) K.E. B) K.E per unit area C) K.E. per unit volume D) K.E. per unit length 1/2 pv2 This term represents the kinetic energy per unit volume of the fluid. 18 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 18) Air is streaming past a horizontal airplane wing such that its speed is 120 m/s over the upper surface and 90 m/s at the lower surface. If the density of air is 1.3 kg/m³ and the wing is 10 m long and has an average width of 2 m, then the difference of the pressure on the two sides of the wing is A) 4095.0 Pascal B) 4.0950 Pascal C) 40.950 Pascal D) 409.50 Pascal From the Bernoulli’s theorem P1-P2=1/2 p (v22-v12 )=1/2 x 1.3 x [(120)2-(90)2 ] = 4095 N / m2 or Pascal 19 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 19) Eight drops of water each radius 2mm are falling through air at a terminal velocity of 8cm/s. If they coalesce to form a single drop, the terminal velocity of the combined drop will be: ETEA 2017 A) 24 cm/s B) 32 cm/s C) 8 cm/s D) 16 cm/s Vt’ = n2/3 Vt, Here n=no. of drops. Thus Vt’ = 82/3 Vt = 4 x 8 = 32cm/s 20 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 20) Terminal velocity is given by the equation A) Vt = 2ρgr²/9η B) Vt = gr² C) Vt = gr²/9η D) Vt = 9gr²/2η Terminal velocity is given by equation Vt = 2rgr2/9h 21 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 21) When a body moves with terminal velocity, the acceleration in the body becomes A) infinite B) variable C) maximum D) zero (Since net force = 0, acceleration = 0.) 22 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 22) Terminal velocity is A) neither uniform nor maximum B) maximum C) uniform and maximum D) uniform (Terminal velocity is the maximum constant speed reached when drag equals weight.) 23 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 23) The pans of a physical balance are in equilibrium. Air is blown under the right hand pan; then the right hand pan will A) Remain at the same level B) Move erratically C) Move down D) Move up According to Bernoulli’s theorem. Blowing air reduces pressure under the right pan (Bernoulli’s principle), increasing the net downward force due to atmospheric pressure on the top side. 24 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 24) The speed of the fluid is maximum in the venturimeter at A) none of these B) convergent duct C) throat D) divergent duct In a venturimeter, the throat (narrowest part) has the highest speed due to the continuity equation (A↓⇒v↑) and the lowest pressure (Bernoulli’s principle). 25 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 25) Find the velocity of discharge through an orifice 2.5 m below the water surface? NUMS-2019 A) 7.0 m/s B) 3.5 m/s C) 6.5 m/s D) 4.0 m/s Explanation: Putting all available values gives V = 7m/s 26 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 26) The working of an atomizer depends upon A) Boyle’s law B) Archimedes principle C) Newton’s law of motion D) Bernoulli’s theorem An atomizer uses high-speed air (low pressure) to draw liquid up a tube and disperse it as droplets, following Bernoulli’s principle. 27 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 27) Water flows through a constriction in horizontal pipe as it enters constriction, water’s: ETEA 2015 A) Speed decreases and pressure increases B) Speed increases and pressure remains constant C) Speed increases and pressure decreases D) Speed increases and pressure increases By the continuity equation, speed increases in narrower sections. By Bernoulli’s principle, pressure decreases where speed increases. 28 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 28) A chimney works best if air exposed to the chimney is A) moving fast B) moving C) moving slowly D) stationary Chimneys rely on pressure differences caused by fast-moving air (Bernoulli’s principle). Faster airflow over the chimney top reduces pressure, enhancing upward draft. 29 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 29) One end of a cylindrical pipe has a radius of 1.5cm. A water stream (density = 1.0 × 10³ kg/m³) flows steadily out at 7.0m/s. The volume flow rate is: Med-ETEA 2015 A) 7.0 m³/s B) 4.9 × 10⁻³ m³/s C) 4.9 m³/s D) 49 m³/s Volume rate V/t =A v=(pr2) velocity = 3.14 x (0.015)2×7= 4.9×10–3 m3/s 30 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 30) A hail and a raindrop of the same radius are released from the same height. The raindrop will reach: ETEA-2019 A) Before hail B) After hail C) At the same time D) None of the above Vt = 2ρ gr2/9ƞ → vt α ρ, ρ of hail is greater than that of drop, so it will attain high terminal velocity. 31 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Fluid Flow 31) Water is flowing through a horizontal pipe of non-uniform cross-section. At the extreme narrow portion of the pipe, the water will have A) Maximum pressure and least speed B) Both pressure and speed maximum C) Both pressure and speed least D) Maximum speed and least pressure By the continuity equation where the pipe is narrower, speed increases.By Bernoulli’s principle, higher speed means lower pressure. 32 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 32) Two fog droplets have radii in the ratio 2:3. Their terminal velocities are A) 4:06 B) 4:03 C) 4:09 D) 2:09 Vt = 2rgr2/9h → v1/v2 = (r1/r2)2 = (2/3)2 = 4/9 33 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 33) Instrument used to measure blood pressure is called A) venturimeter B) sphygmomanometer C) sonometer D) blood pressure A sphygmomanometer is the clinical device for measuring blood pressure. A venturimeter measures flow rate, and a sonometer measures string tension/frequency. 34 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 34) An incompressible liquid flows through a horizontal tube as shown in the following figure. Then the velocity v of the fluid is (Diagram not provided) A) 1.0 m/s B) 3.0 m/s C) 2.25 m/s D) 1.5 m/s If the liquid is incompressible then mass of liquid entering through left end, should be equal to mass of liquid coming out from the right end. ∴M=m1+m2=>Av1=Av2+1.5 A.v → A x 3=A x 1.5+1.5 A.v=>v+1 m/s 35 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Fluid Flow 35) In laminar flow, the velocity of the liquid in contact with the walls of the tube is A) Maximum B) In between zero and maximum C) Equal to critical velocity D) Zero Due to viscosity, the fluid layer in contact with the wall has zero velocity (no-slip condition). Velocity increases towards the center (parabolic profile in a pipe). 36 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 36) Raindrops falling from the sky reach the ground with: ETEA 2009 A) Constant terminal velocity B) Variable acceleration C) Constant acceleration D) Acceleration greater than g Constant terminal velocity because drag force become equal to weight of the poilet after some time 37 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 37) In cricket when a bowler produces reverse swing the ball will move towards A) seam of the ball B) rough side C) goes straight D) shinning side of the ball In reverse swing, the ball moves toward the rough side because turbulent airflow on the rough side delays separation, while the shiny side (smoother) has earlier separation, creating a pressure difference. 38 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 38) In the following fig. is shown the flow of liquid through a horizontal pipe. Three tubes A, B and C are connected to the pipe. The radii of the tubes A, B and C at the junction are respectively 2 cm, 1 cm and 2 cm. It can be said that the (Diagram not provided) A) Height of the liquid in the tubes A and C is the same B) Height of the liquid in the tubes A and B is the same C) Height of the liquid in the tube A is maximum D) Height of the liquid in all the three tubes is the same As cross-section areas of both the tubes A and C are same and tube is horizontal. Hence according to equation of continuity vA=vC and therefore according to Bernoulli’s theorem PA=PC i.e. height of liquid is same in both the tubes A and C. 39 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> equation of continuity 39) Water flows from a 6.0cm diameter pipe into an 8.0cm diameter pipe. The speed in the 6.0cm pipe is 5.0m/s. The speed in the 8cm pipe is: ETEA 2016-Med A) 2.8m/s B) 8.8m/s C) 6.6m/s D) 3.7m/s D1=6 cm and D2=8 cm or R1= 3 cm and R2= 4 cm and v1= 5m/s so by A1V1=A2V2 or r12v1= r22v2→ 32 x 5 = 42 x v2→ v2 = 45/16 =2.8m/s 40 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 40) Venturi meter is a device used to measure: A) Speed of fluid B) Viscosity of the fluid C) Density of fluid D) Pressure of the fluid A Venturi meter measures flow speed by comparing pressure differences between a pipe’s wide and narrow sections (using Bernoulli’s principle). 41 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 41) How much more thumb pressure must a nurse use to administer an injection with a hypodermic needle of inside diameter 0.30 mm compared to one with inside diameter 0.60 mm? NUMS-2015 A) 4 times as much B) Twice as much C) 8 times as much D) 16 times as much For the same flow rate, pressure difference ΔP ∝ 1/r4 (Poiseuille’s law). If the diameter halves, the radius ratio is 1:2, so: ΔP ∝ (1/0.5)4 = 16times higher 42 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Terminal Velocity 42) When the drag force on the object becomes equal to its real weight then the; ETEA 2011 A) Object will fall with terminal velocity B) Object will fall freely C) Object will fall with critical velocity D) Object will become stationary When the drag force on the object becomes equal to its real weight then the Object will fall with terminal velocity 43 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 43) Bernoulli’s theorem applies to: A) Fluids B) Plasma state C) Solids D) Liquids Bernoulli’s principle applies to fluids (both liquids and gases) under the conditions mentioned above. It does not apply to solids or plasma separately. 44 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Fluid Flow 44) A fluid is undergoing incompressible flow, which represents that: ETEA 2016 A) The velocity must be the same everywhere B) The density cannot change with time or location C) Pressure at a given point cannot change with time D) Velocity at a given point cannot change with time Incompressible means that bliquid will not compress and density will remains constant 45 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Bernouli’s Equation and its application 45) A larger water tank open at the top has small hole in the bottom when the water level is 30m above the bottom of the tank the speed of the water leaking from the hole is: ETEA 2015 A) 2.5 m/s B) insufficient data C) 44 m/s D) 24 m/s It can be solved by Torricelli Theorem; As speed is given by ; V =√2gh = √(2×10×30)=24.49 46 / 46 Category: BOMVirtual.com >> Physics >> 06 Fluid dynamics >> Fluid Flow 46) When a fluid is incompressible, the quantity that is constant is: MDCAT-2016 A) Pressure B) Force C) Density D) Mass By definition, incompressible flow implies constant density (ρ=constant). 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