Fluid Mechanics and Hydraulic Machines MCQs 2026

Non-Newtonian fluid example is

1. Ablood or polymer solution✓
2. Bwater at 20 °C✓
3. Cair at low speed✓
4. Dmercury✓

Newton law of viscosity states shear stress is proportional to

1. Arate of strain (velocity gradient)✓
2. Bpressure only✓
3. Cabsolute temperature only✓
4. Ddensity squared✓

Capillary rise in small tube is due to

1. Asurface tension and wetting✓
2. Bonly gravity increase✓
3. Cturbulent mixing✓
4. Dcompressibility✓

Metacentric height GM positive indicates

1. Aalways capsizing✓
2. Bneutral stability only✓
3. Cstable floating equilibrium✓
4. Dno restoring moment✓

Buoyant force on submerged body equals

1. Aweight of displaced fluid✓
2. Bweight of body always✓
3. Chalf displaced volume only✓
4. Dsurface tension force✓

Hydrostatic pressure at depth h in liquid is

1. Aρg/h✓
2. Bh/ρg✓
3. Cρgh✓
4. Dzero at all depths✓

Pascal law in fluid statics states

1. Apressure at a point is transmitted equally in all directions✓
2. Bpressure increases with velocity always✓
3. Cfluid always flows uphill✓
4. Ddensity is constant in gases only✓

Energy grade line (EGL) includes

1. Aonly static pressure✓
2. Bonly elevation✓
3. Cfriction factor value✓
4. Dvelocity head in addition to piezometric head✓

Hydraulic grade line (HGL) represents

1. Avelocity head only✓
2. Bpiezometric head at each point along pipe✓
3. Ctemperature profile✓
4. DRe along pipe✓

Draft tube in reaction turbines serves to

1. Arecover kinetic energy at outlet and maintain suction head✓
2. Bincrease frictional loss only✓
3. Cheat the water✓
4. Dmeasure flow rate only✓

Kaplan turbine is suitable for

1. Avery high head small flow✓
2. Bzero water availability✓
3. Ccompressed air only✓
4. Dlow head and large discharge✓

Francis turbine is classified as

1. Apure impulse only✓
2. Bwind turbine✓
3. Cmixed-flow reaction turbine✓
4. Dreciprocating engine✓

Gear pump belongs to category of

1. Adynamic radial flow pumps✓
2. Bpositive displacement pumps✓
3. Cgravity pumps only✓
4. Dturbines✓

Reciprocating pump delivers

1. Aonly low pressure large flow always✓
2. Bno pulsating flow ever✓
3. Cnearly constant volume per stroke at high pressure✓
4. Donly gases✓

Multistage centrifugal pumps are used when

1. Aonly very low head large flow✓
2. Bhandling pure solids only✓
3. Cvacuum generation only✓
4. Dhigh head is required at moderate flow✓

Specific speed of a centrifugal pump indicates

1. Aonly electrical power factor✓
2. Btype and shape suitable for given Q and H✓
3. Coil viscosity grade✓
4. Dsteam pressure only✓

Cavitation in pumps is indicated by

1. Asilent smooth operation✓
2. Bnoise, vibration and pitting of impeller✓
3. Cincreased NPSHa always✓
4. Ddecreased temperature only✓

NPSH available must exceed NPSH required to avoid

1. Alaminar flow only✓
2. Bincreased viscosity✓
3. Ccavitation in pumps✓
4. Dpositive gauge pressure always✓

Minor losses in pipe systems are caused by

1. Aonly straight pipe friction✓
2. Bgravity alone✓
3. Cfluid density only✓
4. Dfittings, bends, valves and sudden expansions✓

Moody diagram relates friction factor to

1. AReynolds number and relative roughness✓
2. Bonly pipe length✓
3. Conly fluid color✓
4. Dcompressibility only✓

Friction factor for smooth pipes in turbulent region can be estimated by

1. AArchimedes principle only✓
2. BBlasius or Colebrook equation✓
3. CPascal law only✓
4. DCarnot efficiency formula✓

Darcy-Weisbach equation gives

1. Apump power directly✓
2. BReynolds number value✓
3. Chead loss due to friction in pipes✓
4. Dsurface tension force✓

Turbulent flow in pipes is characterized by

1. Airregular fluctuations and mixing✓
2. Bsmooth layered streamlines only✓
3. CRe below 100 always✓
4. Dzero wall shear✓

For laminar flow in a circular pipe, velocity profile is

1. Aparabolic with maximum at center✓
2. Bflat plug flow always✓
3. Clinear from wall to center✓
4. Dzero everywhere✓

Kinematic viscosity is defined as

1. Adynamic viscosity divided by density✓
2. Bdensity times dynamic viscosity✓
3. Cpressure divided by velocity✓
4. DRe times diameter✓

Bernoulli equation for steady incompressible flow along a streamline states that

1. Avelocity head alone is constant✓
2. Bpressure always increases with height✓
3. Ctotal head remains constant✓
4. Dflow rate changes with pipe diameter only✓

Continuity equation for incompressible flow in a pipe is expressed as

1. Ap1 = p2 always✓
2. BA1V1 = A2V2✓
3. CQ changes with viscosity✓
4. DRe is constant everywhere✓

Reynolds number Re is defined as

1. AμVD/ρ✓
2. BVD/g✓
3. Cp/ρV²✓
4. DρVD/μ✓

Dynamic viscosity unit in SI is

1. Am²/s only✓
2. BPa·s (N·s/m²)✓
3. CN/m only✓
4. Dkg/m only✓

Flow in a smooth pipe is generally laminar when Reynolds number is below

1. A4000✓
2. B10000✓
3. C500✓
4. D2300✓

Boundary layer thickness increases along a flat plate because

1. Apressure always decreases✓
2. Bdensity becomes zero✓
3. Cviscous effects diffuse momentum outward✓
4. DRe decreases to zero✓

Centrifugal pump imparts energy to fluid mainly by

1. Aincreasing kinetic energy then converting to pressure✓
2. Bheating the fluid only✓
3. Cdecreasing angular momentum✓
4. Dcompressing vapor✓

Pelton wheel is an example of

1. Areaction turbine only✓
2. Bimpulse turbine✓
3. Cpositive displacement pump✓
4. Dreciprocating pump✓

Hydraulic ram utilizes

1. Asteam expansion only✓
2. Bwater hammer effect to pump a portion of water to higher elevation✓
3. Celectromagnetic induction✓
4. Dcentrifugal impeller only✓

Simple U-tube manometer measures

1. Apressure difference as liquid column height difference✓
2. Bmass flow rate directly✓
3. CReynolds number✓
4. Dturbine power only✓

Venturi meter measures flow rate based on

1. Atemperature rise in throat✓
2. Bpressure difference between converging and throat sections✓
3. Ccolor change of fluid✓
4. Dmagnetic field strength✓

Orifice meter causes greater permanent pressure loss than venturi because

1. Ait has a longer converging cone✓
2. Bit measures temperature instead✓
3. Cdischarge coefficient is unity✓
4. Dno gradual recovery section after restriction✓

Stokes law gives drag on small sphere as

1. AFD independent of viscosity✓
2. BFD proportional to V² only✓
3. CFD = 3πμDV✓
4. DFD zero in viscous flow✓

Terminal velocity of falling particle occurs when

1. Aacceleration is maximum✓
2. BRe is infinite always✓
3. Cdrag force equals net weight minus buoyancy✓
4. Dviscosity is zero✓

Pitot tube measures

1. Astatic pressure only in all cases✓
2. Bmass of fluid✓
3. Cstagnation pressure to find local velocity✓
4. Dturbine efficiency✓

Coefficient of discharge for venturi is typically

1. Azero always✓
2. Bhigher than for sharp-edged orifice✓
3. Clower than orifice always✓
4. Dexactly 1.0 always✓

Rotameter measures flow using

1. Aelectromagnetic induction only✓
2. Borifice plate only✓
3. Cfloat equilibrium in tapered tube✓
4. Dthermocouple✓

Weir flow measurement for rectangular sharp-crested weir varies discharge approximately as

1. AH linearly only✓
2. BH² only✓
3. CH^(3/2)✓
4. Dindependent of head✓

Chezy and Manning formulas estimate

1. Aclosed pipe laminar flow only✓
2. Bvelocity or discharge in open channels✓
3. Ccompressor performance✓
4. DRankine cycle efficiency✓

Hydraulic radius R is defined as

1. Aperimeter divided by area✓
2. Bdiameter squared✓
3. Cvelocity times area✓
4. Dflow area divided by wetted perimeter✓

Froude number characterizes

1. Aviscous to inertial forces only✓
2. BMach number in liquids✓
3. Cpump NPSH✓
4. Drelative importance of inertia to gravity in open channel flow✓

Critical depth in rectangular channel occurs when

1. ARe equals 2300✓
2. Bflow is always subcritical✓
3. CFroude number equals unity✓
4. Ddepth is maximum always✓

Hydraulic jump occurs in

1. Alaminar to turbulent in pipe only✓
2. Bpump suction line only✓
3. Cclosed valve only✓
4. Dsupercritical to subcritical transition✓

Surface tension σ has unit

1. APa·s✓
2. BN/m✓
3. Cm²/s✓
4. Dkg/m³✓

Vapor pressure of liquid is important in pumps because

1. Ait increases pipe roughness✓
2. Bit eliminates friction loss✓
3. Cit raises NPSHa always✓
4. Dlow pressure can cause boiling and cavitation✓

Head developed by centrifugal pump for given impeller speed and diameter is independent of

1. Afluid density✓
2. Bimpeller diameter✓
3. Crotational speed✓
4. Dimpeller design✓

Affinity laws for pumps state flow rate varies with speed as

1. AQ proportional to N²✓
2. BQ proportional to N✓
3. CQ independent of N✓
4. DQ proportional to 1/N✓

System curve for pipe network intersects pump curve at

1. Ashutoff head only✓
2. Bmaximum efficiency always✓
3. Czero flow always✓
4. Doperating point✓

Water hammer pressure surge depends on

1. Aonly pipe color✓
2. Bonly ambient temperature✓
3. CRe only✓
4. Dwave speed and velocity change✓

Surge tank in hydro penstock reduces

1. Aturbine efficiency to zero✓
2. Breservoir volume✓
3. Cnet head permanently✓
4. Dwater hammer pressure fluctuations✓

Impulse turbine runner operates in

1. Ahigh vacuum only inside blades always✓
2. Bpressurized sealed casing only✓
3. Catmospheric pressure region✓
4. Doil bath✓

Degree of reaction for turbine is ratio of

1. Aenthalpy drop in rotor to total enthalpy drop✓
2. Bpower to speed✓
3. Cinlet to outlet pressure only✓
4. Dtorque to angular velocity only✓

Cavitation parameter σ for turbines relates to

1. Aonly steam quality✓
2. BNPSH and net head✓
3. Cfuel air ratio✓
4. DCOP of refrigerator✓

Hydraulic efficiency of turbine is

1. Awater power output divided by energy supplied in flow✓
2. Belectrical output only without losses✓
3. Cvolumetric efficiency of pump✓
4. Dboiler efficiency✓

Inverted U-tube manometer is used for

1. Ahigh vacuum in steam condenser only always✓
2. Bliquid flow in open channel only✓
3. Cmeasuring torque✓
4. Dmeasuring small pressure differences in gases✓

Barometer measures

1. Agauge pressure in pipe always✓
2. Bdynamic pressure only✓
3. Clocal atmospheric pressure✓
4. Dmass flow rate✓

Gauge pressure equals

1. Aabsolute plus atmospheric✓
2. Bvacuum pressure always✓
3. Ctwice absolute pressure✓
4. Dabsolute pressure minus atmospheric pressure✓

Steady flow means

1. Auniform flow at all cross sections always✓
2. Bzero velocity everywhere✓
3. CRe is constant in time only at inlet✓
4. Dproperties at a point do not change with time✓

Uniform flow in open channel implies

1. Aonly steady in time✓
2. Balways supercritical✓
3. Calways laminar✓
4. Ddepth and velocity constant along channel length✓

Streamline is a line

1. Atangent to velocity vector everywhere✓
2. Bperpendicular to flow always✓
3. Calong which pressure is zero✓
4. Dof constant temperature only✓

Path line of fluid particle is

1. Aalways straight line✓
2. Bactual trajectory traced by that particle✓
3. Csame as streak line always in unsteady flow✓
4. Dalways parallel to wall✓

Streak line is

1. Ainstantaneous velocity direction only✓
2. Bconstant pressure line✓
3. Clocus of particles passing through a common point✓
4. Dpipe centerline always✓

Euler equation along streamline for inviscid flow relates

1. Ashear stress to viscosity only✓
2. Bheat transfer to conductivity✓
3. Cpressure gradient to velocity and body force✓
4. Dmass to moles✓

Navier-Stokes equations include

1. Aonly hydrostatic terms✓
2. Bviscous stress terms in momentum balance✓
3. Ccombustion chemistry✓
4. Delectromagnetic forces only✓

Transition from laminar to turbulent pipe flow depends on

1. Apipe material color only✓
2. Bonly pipe length✓
3. CReynolds number and disturbances✓
4. Dabsolute pressure only✓

Hydraulic jump energy loss appears as

1. Aincreased mechanical energy in flow✓
2. Bstored elastic energy✓
3. Cpump head gain✓
4. Dturbulence and heat dissipation✓

Torricelli theorem gives exit velocity from tank as

1. A√(gh/2)✓
2. B2gh without root✓
3. Czero if orifice is sharp✓
4. D√(2gh)✓

Coefficient of velocity Cv for orifice is ratio of

1. Aactual jet velocity to ideal velocity✓
2. Bactual discharge to ideal area velocity product✓
3. Cpressure to density✓
4. Dhead loss to diameter✓

Coefficient of contraction Cc is ratio of

1. Apipe area to orifice✓
2. Bvena contracta area to orifice area✓
3. Cvelocity to discharge✓
4. DRe to friction factor✓

Cd for orifice equals approximately

1. ACv times Cc✓
2. BCv divided by Cc✓
3. CCv plus Cc✓
4. D1 always✓

Blower differs from compressor in that blower provides

1. Avery high pressure ratio like multistage compressor✓
2. Brelatively small pressure rise at high volume flow✓
3. Conly vacuum suction✓
4. Dliquid pumping✓

Axial flow pump is preferred when

1. Alarge discharge at low head is required✓
2. Bvery high head low flow✓
3. Chandling highly viscous paste✓
4. Dmetering precise microliters✓

Foot valve on pump suction line prevents

1. Acavitation entirely always✓
2. Breverse rotation of motor✓
3. Cdrainage of pipe and loss of prime when pump stops✓
4. Dincrease in NPSHr✓

Priming of centrifugal pump is necessary because

1. Acentrifugal pump cannot handle air and must be filled with liquid✓
2. Bit increases impeller diameter✓
3. Cit reduces NPSHa✓
4. Dit converts reciprocating to rotary motion✓

Differential manometer connected across venturi throat and inlet measures

1. Aabsolute atmospheric pressure only✓
2. Bpressure difference used to calculate flow rate✓
3. Cfluid viscosity directly without formula✓
4. Dturbine shaft power✓