GUPTA & GUPTA (CIVIL ENGINEERING MCQs) Vol-01 >» DETAILED & ERROR FREE SOLUTIONS For All State AE/JE, SSC-JE, RRB-JE & PSUs Examinations B. CHAND PUBLICATION 1] 600EP B. Chand Publication Engineers Pride- Most advanced and Honest Institute for UPSC IAS, UPSC IES,GATE,SSC-JE, RRB- JE, State(AEn/JEn),PSUs etc.-By IITian (B.Tech/ IIT Guwahati),Ex. Assistant Commandant(AIR- 06/General), IES(Indian Railways/AIR- 170/General), SSC-JE(AIR-04/General)- B.CHAND, Class Room/Office Address-C-225, Ganesh Marg, C-Block, Mahesh Nagar (500 Meter from Riddhi Siddhi Tiraha), Gopal Pura Mode (between Gandhi Nagar Railway Station and Durga Pura Railway Station), Jaipur, Rajasthan, 9660807149, 7014320833, 8078607812, 9571854248 & 9351143146 iesbirdhi@gmail.com, www.engineerspride.org , www.engineeringpride.com 1% Edition: Sept. 2020 MRP: 815/- Only (Hard copy) & 100/- Only (Note - soft copy available with lifetime validity on Engineers Pride APP) (Hard copy is available on various e-commerce websites such as Amazon, Flipkart etc and Leading bookstores across the country. For soft copy Download Engineers Pride android APP (Education Galaxy Media) Disclaimer - all care has been taken while designing this book but still there might be some error and for more clarity students may refer to video solutions of this book available on Engineers Pride website & App. All State AE/JE & SSC-JE EXAMINATIONs 2020 Copyright © 2020, by 8. Chand Publication. All rights are reserved. No part of this publication may be reproduced, stored in or introduced into a retrieval system, or transmitted in any form or by any means (electronic, mechanical, photo-copying, recording or otherwise), without the prior written permission of the above-mentioned publisher of this book. Stern actions will be taken against who copy even single line of this book, ——————$ Engineer's Pride oy nana es. 25,6 2| 600Index S.No. | Subject Page No. Fi Fluid Mechanics (FM) 5 — 2. Surveying 135 \3. Irrigation Engineering (IE) 1243 4. Highway Engineering (HE) _ 349 L- 5. Railway Engineering (RE) 397 6. Environmental Engineering (EE) 431. 7. Construction Planning and Management 515 8. Docks and Harbour Engineering (DHE) 571 9. Tunnel Engineering (TE) 587 Engineer's Pride oy-wnien &15.incan Ralways-BCHANDSIR | Classranm/OMice Adarest-<-225, Ganesh Mar, C-Block, Mahesh Nagar [200 Meter fom Rida Sia Tite), ops ura Mode Teeter Cana Hagar Raswsy Sain anf Digs Pare Ray Sao), ur, Ratan, S5EON7L, TOLER, O7EEOTELZ 3 | 600—_—_ Engineer's Pride ty-sniona es insan riwoys-cHANDSI|Cnsonn/ Otis Aden 225, mesh Noe EBeck Mabe nap [0D Maes How NOOO 4 | 600——————— Engineer's Pride oy wan 165 /insanatway-8 CAND st | Cssoom/fic Adres: C235, Ganesh Mare ok Maes Hage [200 Mee om i Tne, opal ara Mode ctacen Gandhi Nagar Raiway ston and Outta Pir Ralway Stor, lou, Roshan, SIBOIA2, TOLEZ0832, 27RE0782 ice S | 6001. Pascal-second is the unit of (a) Pressure (b) Kinematic viscosity (c) Dynamic viscosity (d) Surface tension Sol.(c) 2. Anideal fluid is (a) One which obeys Newton's law of viscosity (b) Frictionless and incompressible (0) Very viscous (a) Fi ionless and compressible Sol.(b) Ideal fluid @ which is incompressible and is having no viscosity Ideal fluid is only an imaginary fluid and do not exists in nature. 3. The unit of kinematic viscosity is (a) gm/cm-sec? (b) dyne-sec/em? (c) gm/cm?-sec (d) cm?/sec Sol.(d) Kinematic (onan vient Density of fluid viscosity = SI unit is the (m*/sec) and CGS unit is the stokes 1 stokes = 0.01 cm*/sec = 0.0001 m/sec 4. Ifthe dynamic viscosity of a fluid is 0.5 poise and specific gravity is 0.5, then the kinematic viscosity of that fluid in stokes is (a) 0.25 (b) 0.50 (1.0 (d) None of the above 1 pascal = 1 N/m? Dynamic viscosity or absolute viscosity unit is kg/m sec; Ns /m? and poise. Pressures unit is N/m? pascal Kinematic viscosity unit is stokes, m?/sec Surface tension unit is N/m, dyne/em Sol.(c) Given = 0.5 poise = 0.05 Ns/m? [1 poise = 0.1 Ns/m?] 5 = 0.5 x1000 = 500 ke/m? since kinematic viscosity L = 5 t= Gn) L=1x 10% m/sec Since 1 m?/sec =10* stokes k= 1x104x10* L=1 stokes 5. The viscosity of a gas (a) Decreases with temperature increase in (b) Increases with temperature increase in {c) Is independent of temperature (U) ly independent of pressure for very high-pressure intensities Sol.(b) With In increase in temperature, there is typically an increase in the molecular interchange as molecular move faster in higher temperature. The gas viscosity increases with temperature. —_,)]HApApA Engineer's Pride oy.1nan 16s nsisn always @ CHAN Si | Couronne Aaess sha CBlck, Mesh Nasr (200 Meta rom Ra ge 6 | 600‘Ammonia gas viscosity Let ris the capillary tube of radius at atmospheric resure % ,@ | And height of capillary rise is h gM | —Prmamicviscosiy | « 3 Z| y= specific weigh o = surface te & 2 | Senay | 0 § Y= spe eI Sa |@ 2] 5, from vertical equilibrium gu (281 (ocos 0) = yxm/4 d xh du 02 24 S| Where d= dia. of capillary tube E i pa jet] (d=2n é é ne ® Taking 9 = 0, cos @=1 au by 0 0 50 100 150 200 20 3m 350 0 450 nae Tepe aha 6. Newton’s law of viscosity relates (a) Intensity of pressure and rate of angular deformation {b) Shear stress and rate of angular de- formation (c)Shear stress, viscosity and temperature (d)Viscosity and rate of angular deformat ” Sol.(b) Newton's law of viscosity states t « $2 Where t = shear stress do SE = rate of angular deformation arxcoss 7. The rise of specific weight 7 in a capillary tube of radius ris given by o 2a eo b) 22. on (o) = 2 wo (@) 7 2r Where Cis the surface tension of the liquid? Sol.(c) —— eee Engineer's Pride »-mon CHANDOS Cossour fice Are-295 Gans Mar. C80 Mahe wate) cops Pes Mode (between Gantt Mage Raway Staten and Dua Pura Rafat, Joni, Raton, 96607 7 | 6008. The intensity of pressure developed by surface tension of 0.075 N/m in a droplet of water of 0.075mm diameter is (a) 0.8 N/cm? (b) 0.6 N/cm? (c) 0.4 N/em? (d) 400 N/cm? Sol.(c) Intensity of pressure developed in water droplet due to surface tension AP = @) 50, ap =(—1*9075 107Sx10~ 4000 N/m? Or AP= 0.4 N/m? 9. Surface tension of water (a)Increase with ‘decrease in temperature (b) Decreases with decrease in temperature {c) Is independent of temperature (d) None of above Sol.(a) Surface tension is a cohesive type of force with decrease in temperature cohesion between molecules of fluid increase thus surface tension increase. Surface Tension 60 of Water Surface Tension (dynelem) Temperature (°C) 10. One kilo-pascal is equivalent to. (a) Only when fluid is frictionless and incompressible (b) 1000N/m? Pride onan ies nneanRalnays-8 HAND SI) Cro. (c) 1000N/mm? (d) 1000N/em? Sol.(b) 1 kilopascal = 1x 10° N/m? [1 pascal = 10? N/m?] ‘Lkilo pascal = 1000 N/m? 11. Ifa liquid has greater cohesion than adhesion with the solid, then the liquid in the capillary tube will (a) Rise with concave surface upward (b) Rise with convex surface upward (c) Depress with concave surface upward (d) Depress with convex surface upward Sold) @<9 | Cohesion | Wetting of | Concav | Rise in oe |< surface |e top | capillary adhesion surfaces | tube “<9 | Adhesion | Does not | Convex | drop in @ |< wets the | top | capillary Cohesion | surfaces | surface | tube 12. Examine the following four statements. (i) Surface tension is due to cohesion only. Capillarity is duc to adhesion only. Surface tension is due to both cohesion and adhesion. (iv) Capillarity is due to both cohesion and adhesion. Which of the above statement are true? (a) (i) and (ii) (b) (ii) and (ii) (c) (i) and (iv) (d) only (iv) Sol.(c) 8 | 600Surface tension occurs due to cohesion only. Capillary effect due to adhesion and Surface tension both. 13. Pressure of 200 kPa is equivalent to a head of x metres of carbon tetra- chloride of relative density 1.59 where xis equal to (a) 11.62 (b) 11.92 (¢)12.82 (a) 13.12 Sol.(c) Since pressure P = 6gh Here G = 1.59, Hence 6 = 1.59 x1000 P = 200 kPa d= 1590 kg/m? So, 200 x 10? = 1590 x 9.81 x h > h=1282m 14, For a vertical semi-circular plate, submerged in a homogenous liquid with its diameter ‘d’ at the free surface, the depth of centre of pressure from the free surface is 3ad 3d aes b) —— i) re 4d 3ad eae dye a 3a cy 16 Sol.(a) Centre of pressure: Point of application of the total pressure on the surface Cop ata distance h from free surface ta het la = MOI about Ca h= distance of ca from free surface Centroid (*, ¥) 15. The pressure intensity is same in all directions at a point {a) 1N/mm? (b) Only when fluid is frictionless at rest {c) Only when fluid is frictionless (d) When there is no relative motion of one fluid layer relative to other Sol.(d) The pressure intensity is same in all directions at a point when fluid is at rest and no relative motion of are fluid layer relative to other one but not needed to be frictionless 16. An open tank contains 1 m deep water with 50cm depth of oil of specific gravity 0.8 above it. The intensity of pressure at the bottom of tank will be (b) 10 KN/m? (d) 14 KN/ m? (a) 4 KN/m? (c) 12 KN/m? Sol.(d) '50 cm oil = 800 kg/m? water Lm Water = 1000 kg/m? Engineer's Pride oy wrone1rs/indanAeiwoy 8CHAND Sm | Canoan/ OMe Adee C225, ares Mag Clk, Mahesh Nag (200 ete rom HS 9 | 600Pressure P = 6gh (Taking g = 10/sec?) P = (800 x 10 x 0.5) + (1000 x10x1) 14 kKN/m? 17. The position of canter of pressure ona plane surface immersed vertically in a static mass of fluid is {a) At the centroid of the submerged area (b) Always above the centroid of the area (c) Always below the centroid of the area (d) None of the above Sol.(c) For vertically immersed body centre of pressure is at / from free surface Centre of pressure h’ G + 4) (i) By equation 1 is clear that h’ >h fs ince s+ Fully Submerged 18. A vertical triangular area with vertex downward and altitude ‘h’ has its base lying on the free surface of a liquid. The centre of pressure below the free surface is at distance of Engineer's Pride o,-1riana its naan Tah), Gepal Pura Made etween Ganehi Nagar Rainy Staton ant Dirgs Pura Relay Sen) (a) (b) = 4 3 h 2h i a 4) Fe It tends to more down word and it may finally sink | * | ‘ 23. Metacentric height for small values of angel of heel is the distance between the (a) Centre of gravity and centre of buoyancy 11 | 600(b) Centre of gravity and metacentre (c) Centre of buoyancy and metacentre (d) Free surface and centre of buoyancy Sol{b) Meta centre: - It is defined as the point about which a body starts oscillating when the body is tilted by small angle. Metacentric Height: - The distance between the meta centre of a floating body and centre of gravity of body is called metacentric height. 24, A floating body is said to be in a state of stable equilibrium (a) When its metacentric height is zero (b) When the metacentre is above the centre of gravity (c) When the metacentre is below the centre of gravity (d) Only when its centre of gravity is below its centre of buoyancy (es 95} Sol.(b) A floating body is said to be in a state of stable equilibrium when the metacentre is above the centre of gravity ‘Centre of gravity ard) Santee } Paty immerse 25, The increase in metacentric height (i) Increases stability (i (iii) Increases comfort for passengers Decreases stability (iv) Decreases comfort for passengers The correct answer is (a) (i) and (b) (i) and (iv) (c) (ii) and (iii) (d) (ii) and (iv) Sol, (b) The Increase is meta-centric height reduces the time period of oscillating body which is quite uncomfortable for passengers. 26. rectangular block 2m long, 1m wide and 1m deep floats in water, the depth of immersion being 0.5m. If water weights 10kN/m?, then the weight of the block is (a) 5 KN (b) 10 KN (c) 15 KN (d) 20 KN Sol.(b) From Archimedes principal W =Fs Here buoyant force Fs = weight of fluid displaced by block So, Fs =(YLBH) Fs = 10 x2x1%0.5 Fa =10 KN Hence weight of block W =10 KN Sa Taare Pride oy-1nan 1¢5 naan tatway 8 OND Tahal, Gopal Pus Hode (between Gane Maer Rly Satin ad 12 | 60027, The point in the immersed body through which the resultant pressure of the liquid may be taken to act is known as (a) Centre of gravity (b) Centre of buoyancy (c) Centre of pressure (d) Metacentre Sol{c) Centre Of pressure: - The Point in the immersed body through which resultant pressure of the liquid may be taken to act. 28. A vessel containing liquid moves downward with a _—_constant acceleration equal to “g”, then {a) The pressure throughout the liquid mass is atmospheric (b) There will be vacuum in the liquid {c) The pressure in the liquid mass is greater than hydrostatic pressure (d) None of the above Sol.(a) Fluid at rest p= | ig A vessel containing liquid Moring down ward with constant acceleration ‘g’ Given, Here a=g P pgh(1 S “) 9 P =0 (Atmospheric) 29. When a liquid rotates at a constant angular velocity about a vertical axis as a rigid body, the pressure intensity varies (a) Linearly with radial distance (b) As the square of the radial distance (c) Inversely as the square of the radial distance (d) Inversely as the radial distance Sol.(b) In vortex flow pressure gradient in radial a _ sya Direction (32 = 5w?r) 2 ap- be Por? 30. Anopen cubical tank of 2m side is filled with water. If the tank is rotated with an acceleration such that half of the water spills out, then the acceleration is equal to Engineer's Pride oy iar ¢/min fotwon @CHANO 3h | Gruroun/Ofic Asrex.235, Ganan Marg lock Manes Nga (200 Meer om Toto), Soot Pia Mode eetacen Goh Naga’ Rawey Staton and Bugs Pore Rodway Sten), lpi, Aeon, SESEOTSS, TOLSZO88, A7HEOTSIZ 13 | 600(a) 8/3 (b) g/2 (c) 28/3 (dg Sol.(d) oe Tan 0 == a Take is accelerated with an accelerated such that half of water spills out. o= 450 Tano = tantan45° = £ 9 9 >a=g 31, Aright circular cylinder open at thetop is filled with liquid and rotated about its vertical axis at such a speed that half the liquid spills out, then the pressure intensity at the centre of bottom is (a) Zero (b) One-fourth its value when cylinder was full (c) One-half its value when cylinder was full (d) Cannot be predicted from the given data [cs 93, £5 97) Sol.(d) If a right circular cylinder, open at the top, is full of water is rotated a such a speed that half of the liquid spill out then the free surface will touch the bottom at the centre. So, at that point gauge pressure is zero. 5 Pride wy wan resins Zz (@) 32. The horizontal component of force on a curved surface is equal to the (a) Product of pressure intensity at its centroid and area (b) Force on a vertical projection of the curved surface (c) Weight of liquid vertically above the curved surface (d) Force on the horizontal projection of the curved surface Sol.(b) SS , Consider a curved surface AB Fu= 8 gf hda sind = total pressure force on the projected area of the curved surface on its vertical plane Fy = 6 gfhdAcos@= weight of liquid supported by the curved surface upto free surface of liquid, 33. A closed tank containing water is moving in a horizontal direction along a straight line at a constant speed. The tank also contains a steel ball and a bubble of air. If the tank is decelerated horizontally, then 14 | 600(i) The ball will move to the front The bubble will move to the front (i (iv) The bubble will move to the rear The ball will move to the rear Find out which of the above statement are correct? (a)(i)and (i) (b) (i) and (iv) (c) (ii) and (iii) (d) (ili) and (iv) Sol.(b) Rear Front A A 8 bubble aa m m ITI The initial surface of liquid horizontal (AB) Due to acceleration new surface A ‘8’ tan 0= a Due to deceleration Ball will more to the front due to inertia force and bubble will move to rear. 34, The eddy viscosity for turbulent flow is (2) A function of temperature only (b) A physical property of the fluid. (c) Dependent on the flow (d) Independent of the flow Sol.(c) Since shear stress in turbulent flow T= Tvscosity + turbulence +95) Where, n= eddy viscosity = fluid characteristics Engineer's Pride oy iran 815 ian aiwaye acsaNOS | Casseons av ; 7 (2) = flow characteristics 35. Flow at constant rate through a tapering pipe is (i) Steady flow (ii) Uniform flow (iii) Unsteady flow (iv) Non-uniform flow The correct answer is (a) (i) and (ii) (b) (i) and (iv) ()(ii) and (iv) (d) (il) and (iv) Sol.(b) © ®@ 0 ® Steady flow2i flow in which the fluid characteristics do not change with time. Uniform flow 8 flow in which velocity at given time does not change with respect to space. Since the cross section of pipe is not constant therefore the velocity change with change in position. 36. In a two-dimensional incompressible steady flow around an airfoil, the stream lines are 2 cm apart at a great ance from the airfoil, where the velocity is 30m/sec. The velocity near the airfoil, where the stream lines are 1.5cm apart, is (a) 22.5m/sec. —_ (b) 33 m/sec. (c) 40m/sec. _(d) 90m/see. Taha, Gopal Pus Mode (eeween Gavch Hagar Aun Siton and urea Pura Panay San, Japu, Roshan, 9 15 | 600Sol.(e) Since flow per unit width is same at both positions Qs =Q AN =AWV2 230 = 1.5% V2 V2= 40 m/sec pv 37. The equation 24” +2 constant w 2g is based on the following assumptions regarding the flow of fluid: (a) Steady, frictionless, incompressible and along a streamline (b) Steady, frictionless, uniform and along a streamline (c) Steady, incompressible, uniform and along a streamline {d) Steady, frictionless, incompressible and uniform Sol.(a) Bernoull’s equation Pv? —+>—+2) = constant wy Following are the assumption made in the derivation of Bernoulli’ equation (i) Fluid is ideal i.e. viscosity is zero (ii) The flow is steady (ii) The flow is income risible (iv) The flow is irrotational and along a stream line. 38. When the velocity distribution is uniform over the cross- section, the correction factor for momentum is (ao (b) a (c) 4/3 (d)2 Sol.(b) Momentum correction = momentum per second based on factor (8) ‘momentum per second based on Actual veloc ‘momentum per second bas ed onaverage velocity a ia) Be Since velocity Porn is uniform V = Vv, 39. Least possible value of correction factor for (i) Kinetic energy is zero (ii) Kinetic energy is 1 (iii) Momentum is zero (iv) Momentum is 1 The correct statement are (a) (i) and (ii) (b) (ii) and (iii) (6) (i)and (iv) (a) (i) and (iv) Sol.(d) Kinetic energy correction factor 3 (vara) 44 A When v = Vaya Then = 1 Similarity momentum correction factor (vasa) #4 A When V = Vavg Then B= 1 So least possible value of « & fis 1 for both 40. If the velocity is zero over half of the cross-sectional area and is uniform over the remaining half, then the momentum correction factor is -— sO Engineer's Pride p ne san Ths), Gopal Pure Mode (between Gand: Nagar Raway ation” an Dues Ray Son), Isp, Haan, 50807149, 735920633,”B07807512 16 | 600(a) (b) 4/3 (c)2 (aa Sol.(c) Momentum correction factor 2 pe f (c) “ A A SZVdA (2 A + fava i ae Yaug = 5 atv BG) 8 A Be2 41. If velocity is zero over 1/3rd of a cross section and is uniform over remaining 2/3rd of the cross-section, then the correction factor for kinetic energy is (a) 4/3 (b) 3/2 (9) 9/4 (d) 27/8 Sol.(c) : e (ua) A And, Vavg = 2 — Varg? O (given Jo! + (unifrom) 3,5 z] 2 dA=— Engineer's Pride oy wnanaes.o Irate, Gop Fue ode (berween Gand Nagar Aalway Staton. 3 nlmay 8EHANDSA] Oxzroor/Omee 277, Al zal 31 _9 en" 42. The continuity equation PrA.Vi = p2A2V2 Is based on the following assumption regarding flow of fluid (2) Steady flow (b) Uniform flow (c) incompressible flow (d) Frictionless flow Where pyand p, are mass densities. Sol.(a) Continuity equation is based on conservation of mass BAW; 2A2Ve valid for steady and both compressible and incompressible flow 43, In the most general form of Bernoulli's equation +z constant, 28 Each term represents (a) Energy per unit mass (b) Energy per unit weight (c) Energy per unit volume (a) None of the above Sol.(b) Bernoulli's equation nye 5 Gtata= constant al = pressure energy per unit weight of fluid or pressure head = kinetic energy per unit weight or kinetic head po Pro Ralway Stor, Iso, Aja, SGOEOTISS, 7OLEIIE, sORKO7812 17 | 600‘= potential energy per unit weight or potential head. 44, which of the following velocity potentials satisfies continuity equation? (a) x*y (b) x? -y? (c) Cos x (d) xP + Sol.(b) Continuity equation states ( and —22 ox continuity equation’ 45. The magnitude of the component of velocity at point (1,1) for a stream function w= x" is equal to (a)2 b) 2v2 (4 (d) v2 Sol.(a) *, point (1,1) Engineer's Pride oy-nan nn aways-BcHaNO S| caswaon/Otee Aas C725, Coes Wa Trak, opal Para Mode (between Gandhi Mega alway Using At (1, 1) (u, u) = (2, 2) Velocity v= Vu +? = 242? va22 46. The motion of air mass in a tornado is a (a) Free vortex motion (b) Forced vortex motion (@)Free vortex at centre and forced vortex outside (d)Forced vortex at centre and free vortex outside Sol. (d) Forced vortex flow: - some external torque is required to rotate the fluid, rotates at constant angular velocity w. v=wr Centre of air mass there is forced vortex flow Var Free vortex flow: - no torque required vr= constant At outer side there is free vortex v a ~ 47. _ Ina forced vortex motion, the velocity of flow is (a) directly proportional to its radial distance from axis of rotation (b) inversely proportional to its radial distance from axis of rotation 18 | 600{c) inversely proportional to the square of its radial distance from the axis of rotation (d) directly proportional to the square of its radial distance from the axis of rotation Sol. (a) In forced vortex flow some external torque is required to rotate the fluid rotates at constant angular velocity w wr (w= constant) vor Tatty Free vortex Forced vortex 48, Streamlines and path lines always coincide in case of (a) Steady flow (b) Laminar flow (0) Uniform flow (d) Turbulent flow Sol. (a) Streamline: - It is an imaginary line drawn in the flow field such that the tangent drawn at any point on this line represents the direction of velocity vector of the fluid particle at that point. —> Two stream lines cannot intersect each other. Path line: - Actual path traversed by a given fluid particle > Two path lines can intersect each other —> Apath line can intersect itself — In steady flow; stream lines and path lines coincide 49. The kinetic energy correction factor is (a) Applied to continuity equation I v (b) E —||>| 44 (b) Expressed as “AF Levy Expressed as —[|~| da (c) Expressed as +((2) 1 v (d) E> das —|| — [dd (d) Expressed as +) Sol. (c) Kinetic energy correction factor K.E per second based on actual velocity KE per second based on average velocity j (2): dA 50. The momentum correction factor for the velocity distribution shown in fig.1.1 is Uo Yo V ly (a) 1/3 (b)2 (c) 4/3 (d)2 Sol. (¢) EP's Pride oy 1ron \¢5naanalways-®cvAND IR Clasfoon/Oee deren: 225, Cones Mar lac Mahesh Nag [20 Meter rom Ra Sesh TWh, Gopal Pie Moe Toetween, Good Naga” Ray Staton and urea Pura Ralnay Sao), Jou, Rasihan, SEEDN7I68, TOLAZON3, sO7aEO7S12 19 | 600Yo Yo y fj dA 2 Vos A Area = 1x y, = y, (Assume width =1) Ff = 51. Equation of continui principle of conversation of (a) Mass (b) Energy (c) Momentum (d) None of the above Sol. (a) Continuity equation is based on the principal of conservation of mass PAV, = p,AV, 52. In steady flow of a fluid, the total acceleration of any fluid particle {a) Can be zero (b) Is never zero (c) Is always zero (d) Is independent of coordinates Sol. (a) Total Acceleration = f (x, y,2,t) Fagor ‘fecterrion For steady flow local acceleration is zero and convective can zero. 53. The pitot tube is used to measure (a) Velocity at stagnation point (b) Stagnation pressure (c) Static pressure (4) Dynamic pressure Sol. (b) Pitot tube used for measuring the velocity of flow at any point in a pipe/channel. —> Stagnation pressure measuring using a pitot tube By Bernoulli’s equation +5 points (1) and (2) are on the same line and point (2) is stagnation point Ssh Engines Je tyvton aes woys-BCHAND SIR | Casrenr/Oties Adore C25, Gr Traba, Gaal Pra Made (tween Gane Naga Ralway Staton sed Ours Pr Ray taba), Iu, ie 20 | 600=>, =0 2 H+ 40=(h+H)+0+0 2g Pehl This is theoretical velocity. 54, Hot wire anemometer is used to measure (a) Discharge (b) Velocity of gas (c) Pressure intensity of gas (d) Pressure intensity of liquid Sol. (b) The hot wire anemometer is a device used for measuring the velocity direction of the fluid. This can be done by measuring the heat loss of the wire which is placed in the fluid stream. The wire is heated by electric current. 55. The theoretical value of coefficient of contraction of a sharp-edged orifice is (a) 0.611, (b) 0.85 {c) 0.98 (d)1.00 Sol. (a) Coefficient of + contraction (ce) trea of Jet at vena contracta ‘area of orifice The value of c- varies from 0.61 to 0.69 For a sharp-edged or “ideal” circular orifice cc =0.611 56. Which of the following is used to measure the discharge? (a) Current meter (b) Venturimeter (Pitot tube {d) Hotwire anemometer Sol. (b} Current meter, pitot tube and hotwire anemometer used to measure the velocity, whereas the venturimeter is used to measure the discharge. 57; The pitot static tube measure (a) Stagnation pressure (b) Static pressure (c) Dynamic pressure (d) Difference in total and dynamic pressure Sol. (c) Pitot static tube measure the piezometric head at the same point where velocity is to be measured i.e. dynamic pressure. | {| 1 motte } 58. A fluid jet discharging from a 4cm diameter orifice has a diameter 3cm at its vena contracta. If the coefficient of Engineer's Pride oy rimaies non taimep 8C0NDSI | Casvon/OteeAtarea-C225, Ganesh Marg Cl Mates) Naar AD Net om Reh ih Tal Gol Pra ace tecen Gnadh: Regt Balwny sation. and Dutta Pura aly Sat), Jam, Rajon, SSIES, 7OLe2I6, 607R607812 21 | 600velocity is 0.98, the coefficient of discharge for the orifice will be (a) 0.98%(0.75)" (0.75)° 098 (c) 0.98x(1.33)° 0.98 i (1.33) Sol.(a) > Since coefficient of discharge c, =c,c, a/4x(3)° Here ¢.= = (0.75) . w/ax(ay ) ss ¢, = 0.98 So c¢, =0.98x(0.75)" 59. The energy loss in orifice flow is given by (a)H (1-0) (b) HH wl) ani | (a)H +) we wi Where w is coefficient of velocity and His head on orifice. Sol. (a) Vena contracts Applying Bernoulli's eqn. between 1 & 2 Engineer's Prides; riasaiess esOfie saan 25,6 2 PL =H and 2 =o (atmospheric) Ps PS Since (v, <<< v,) H+0+0=22 2g 60. Select the incorrect statement. (a) The pressure intensity at vena contracta is atmospheric. (b)Contraction is least at vena contracta, (c) Stream lines are parallel throughout the jet at vena contracta. (d) Coefficient of contraction is always less than one Sol. (b) Vena contract is a point in a fluid stream where the diameter of stream is least, and fluid velocity is at its maximum. 22 | 600' Vena contracta Recirculation zone low pressure 61. _ Size of a venturimeter is specified by (a) Pipe diameter (b) Throat diameter (c) Angel of diverging section (a) Both pipe diameter as well as throat diameter Sol. (d) Venturi-meter is a device used to measure discharge. It consists of three parts (a) A short converging par (b) throat (c) Diverging part Discharge O = = f[a,a] 62. Due to each end contraction, the discharge of rectangular sharp crested weir is reduced by (a) 5% (b) 10% (c) 15% (d) 20% Sol. (b) Discharge through rectangular sharp crested weir orn oan Now effective length L =(L-0.1x2xH) Hence discharge reduced by 10% from each end contraction. 63, The discharge through a V- notch varies as {a) Ht? (b) HY (He? (d) Ho Where H is head. Sol. (c) Discharge over a ‘V’ Notch => o-Se, tand x/2gxH 2 64. Which of the following is an incorrect statement? (a) Coefficient of contraction of a venturimeter is unity. (b)Flow nozzle is cheaper than venturimeter but has higher energy loss. (c) Discharge is independent of orientation of venturimeter whether itis horizontal, vertical or inclined. {d)None of the above statement is incorrect. Engineer's Pride oy-wnan ues naan rev 205, Ganesh Mor Cah Mahesh Nagar GOD Metr ar eS 23 | 600Sol. (d) Statements (a), (b), (c), all are correct. 65. Coefficient of velocity of venturimeter (a) Is independent of Reynolds number (c)ls unindependent of Reynolds number (c)ls equal to the coefficient of discharge of venturimeter (d) None of the above Sol. (c) For venturi-meter c, =¢,c, (=) fe 66. The pressure at the summit of a syphon is (a) Equal to atmospheric (b) Less than atmospheric (c) More than atmospheric (d) None of the above Sol. (b) syphon summit > Two reservoirs are separated by the hill > They are connected by syphon, highest point is summit > The flow through the siphon is only possible if the pressure at the point C (summit) is below the atmospheric pressure. 67, AY between two stream lines represents (2) Velocity (b) Discharge () Head (4) Pressure Sol. (b) Ay =y.—-W, = AQ, Discharge between two points. 68. Coefficient of velocity for Borda’s mouthpiece running full is (a) 0.611 (b) 0.707 (c) 0.855 (d) 1.00 Sol. (b) A short cylindrical tube attached to an orifice in such a way that the tube projects inwardly toa tank, itis called an internal mouthpiece. It is also called Borda’s Mouthpiece. © Coeffici nt of velocity: (1) Borda's Mouthpiece running full = 0.707 (2) Borda’s Mouthpiece running free = 1.0 (Since No loss of head) ge 24 | 60069. Coefficient of discharge for a totally submerged orifice as compared to that for an orifice discharging free is (a) Slightly less (b) Slightly more (c) Nearly half (d) Equal Sol. (a) Since in submerged orifice due to losses and flow resistance ca will be light lesser as compared to discharging free so corresponding discharge will also be less. 70. The major loss of energy in long pipes is due to (a) Sudden enlargement (b) Sudden contraction {c) Gradual contraction or enlargement (d) Friction Sol. (d) Energy losses in pipe Major losses Minor losses a) sudden enlargement Due to friction b) sudden contraction ©) Bend in pipe 4) pipe fitting ) an obstruction in pipe 71. Coefficient of contraction for an external cylindrical mouthpiece is (a) 1.00 (b) 0.855 (0.711 (c)0.611 Sol. (a) For external cylindrical mouth piece (i) Coefficient of contraction Area of jet at outlet ae ‘Area of Mouthpiece at outlet (ii) Coefficient of velocity c, = 0.855 (ii) coefficient of discharge c, =¢. <¢, ¢, = 0.855 72. Which ofthe following has highest coefficient of discharge? (a) Sharp edged orifice (b) Venturimeter {c) Borda's mouthpiece running full (4) Cipoltetti weir Sol. (b) ~ For sharp edged orifice Cs= 0.611 > for venturimeter Ca = 0.94 - 0.98 (c-=1) > Borda's Mouthpiece, running full Cs = 0.707 (C.=1) Running free Cs = 0.50 (C.=1) > Cippolletti weir Cy = 0.61 (Trapezoidal weir) 73. In Sutro weir, the discharge is proportional to (ay Hi? (b) He (oH? (a) H Where H is head. Sol. (d) Proportional weir also known as sutra weir is a weir whose shape is so designed that nays -@CHAND S| Cahvonm/Otie Adee 225, Ganesh Mar Clk, Manes aga {200 ete om 25 | 600the discharge over the weir is proportional to 8 Oo the head of water over the crest. (b) 15% 2g tan 5 H Q= (constant) x H 2 , (0) $C, 2x (t—-0.2H)H"* (8) 2¢,\2gh™ Where symbols have their usual meanings. Sol. (a) Discharge through a cipolletti weir is given by Q= 76. The equation r= 74, The discharge over a broad crested through circular tubes, wh i weir is maximum when the depth of ae shear stress at distance r from centre, flow is is applicable for (a) H/3 (b) H/2 (a) Laminar flow only (c) 2H/S. (d) 2H/3 (b) Turbulent flow only Where H is the available head. (€) Critical flow Sol. (d) (d) Both laminar and turbulent flows Discharge over the broad crested weir is given by 0 =¢,Lh/2g(H-h) come O- L,)2¢ (Hn? —1) dl R For discharge to be maximum ( 22 | dh = z 2H 3 Because in deriving the above equation, no 75. The discharged through a Cipolletti assumption has been made as to the nature of weir is given by flow. 77. The ratio of maximum velocity to 2, z (a) 3 on 2gLH® average velocity for steady flow between fixed parallel plates is Engineer's Pride oy.rions 1s nsont Wl, Gopal Pars Mode Tintween Gandhi Nagar Aalay Stson nd Dubs Pra 26 | 6002 4 £ b) = {a) (3 3 3 (c) z (a2 Sol. (c) For laminar flow between parallel plates We Vu == (2%) Bul ax a “ae 2 oversea Gx V, so |x 2 Voy 2 78. Which of the following statement is correct? (a) Lower critical Reynolds number is of no practical significance in pipe flow problems. (b) Upper critical Reynolds number is significant in pipe flow problems. (c) Lower critical Reynolds number has the value 2000 in pipe flow (4) Upper critical Reynolds number is the number at which turbulent flow changes to laminar flow. Sol. (c) VD Reynolds's number R, -(2 } H p= Density of fluid D = Diameter of pipe V= Velocity of fluid = Dynamic viscosity of fluid IP R, $2000 => Laminar flow (lower critical limit) 2000 < Re < 4000 => transition flow Re > 4000 => Turbulent flow (upper critical limit) 79. For a sphere of radius 15cm moving with a uniform velocity of 2 m/sec through a of specific gravity 0.9 and dynamic viscosity 0.8 poise, the Reynolds number will be {a) 300 (b) 337.5, {c) 600, (d) 675, Sol. (*) No option is correct. Given .= 0.8 poise = 0.08 Ms/m? V=2m/sec ).9 x10? = 900 kg/m? 0 cm =0.3m d Reynold number R, (22) Hu 900x 20.3 ee -( 0.08 ) R, =6750] 80. The shear stress distribution for a fluid flowing in between the parallel plates, both at rest, is {a) Constant over the cross section (b) Parabolic distribution across the section {c) Zero at the mid plane and varies linearly with distance from mid plane (d) Zero at plates and increases linearly to midpoint Sol. (c) Shear stress distribution for parallel plates both at rest ee eine Engineer's Pride oy man DR Cassoum/Ofce dest 225, Ganesh War. Cac, Maes) Naar 0D Meter or Rd Sh 27 | 600Of since P and t are constant ox Hence T varies linearly with y (7 )max at y = 0 or at the walls of plates 7 =0 L when y= — 2 (c) Semi-log plot of friction factor against Reynolds number {d) Semi- log plot of friction factor against relative roughness Sol. (a) Stanton Diagram: - Log-Log plot of the airflow friction coefficient against the Reynold’s number. Pot Sis Ro, or TS-2545; = S42 MPa y= 026 Wg, 618K 81. _ If x is the distance from leading edge, co w then the boundary layer thickness in laminar flow varies as (a) 2? toyx' (°° (a) x” {cs'93) Sal. (a) If x is the distance from leading edge, then the boundary layer thickness in laminar flow varies as: 82. Stanton diagram is a (a) Log: log plot of friction factor against Reynolds number {b) Log-log plot of relative roughness against Reynolds number Engineer's Pride p-1on e165 mi ‘Raynoids number (Re,)|-) 83. The depth ‘d’ below the free surface at which the point velocity is equal to the average velocity of flow for a uniform laminar flow with a free surface, will be (a) 0.423 D (b) 0.577 0 (c) 0.223 D (d) 0.707 9 Sol. (b) For Veni = V, 84. The boundary layer thickness in turbulent flow varies as (a) x1/7 (b) x12 (oxt5 (a) 23/5 [es 93] Joe ers .225, Gara Wa Bk Mahe Nag RDNte fo WANS 28 | 600Sol. (c) The boundary layer thickness in turbulent flow varies as: 85. The distance y from pipe boundary, at which the point velocity is equal to average velocity for turbulent flow, is (a) 0.223R (b) 0.423 R {0577 R (4) 0.707 R where Ris radius of pipe. Sol. (a) Velocity distribution for turbulent flow in terms of average velocity u-w MOM 25,75 logio| & |+3.75 u R Given u=u 0=5.75 log,, (2) +3.75 log,, (2) =~0.6521 R toeu(2)= log, (0.2228) y= 0.2228R) 86, If a sphere of diameter1 cm falls in castor oil of kinematic viscosity 10 stokes, with a terminal velocity of 1.5 cm/sec, the coefficient of drag on the sphere is (a) Less than 1 (b) Between 1 and 100 (c) 160 (a) 200 Sol. (c) Given: - D = 1 cm = 0.01 m, L = 10 stokes =10x 10¢m’/s v, =1.Som/s =1.5x107m/ sec 2410x104) _ 15x10? 0.01 87... In case of an air flow Occurs il, the separation of (a) At the extreme rear of body (b) At the extreme front of body {c) Midway between rear and front of body (d) Anywhere between rear and front of body depending upon Reynolds number Sol. (a) For streamlined bodies like airfoil whose surface coincides with the streamlines, when the body placed in a flow. In that case the separation of flow will take place only at trailing edge or rearmost part of body x 7” = ») = ) a a 88. When an ideal fluid flows past a sphere, Engineer's Pride oy wnat 1c /sintotwoy- 8ONDSIN| Caswoon/Ofee Ae-C225, Ganesh More Coc, Mahesh agar [200 Nee om Tinks Gop ura ate (between Gendt Nogae alway station and Dues Pura Ray Saon) Jot asthan, GEO90769, 7OLEzO8, 9078807 28 | 600(a) Highest intensity of pressure occurs around the circumference at right angles to flow (b) Lowest pressure intensity occurs at front stagnation point (c) Lowest pressure intensity occurs at rear stagnation point (d) Total drag is zero Sol. (d) If fluid is assumed ideal and body is symmetrical such as sphere, both drag, and lift will be zero. 89. With the same cross-sectional zrea and immersed in same turbulent flow, the largest total drags. will be on (a) A circular disc of plate held normal to flow (b) A sphere (c) Acylinder (d)A streamlined body Sol. (a) Total Drag = (pressure Drag + friction Drag) When body placed perpendicular to flow: Total Drag = (pressure Drag + 0). and pressure drag will be large in case of circular disc, 90. In which of the following the friction drag is generally larger than pressure drag? (a) A circular disc or plate held normal to flow (b)A sphere (©) Acylinder (d) An airfoil Sol. (d) In streamlined body friction Drag > Pressure Drag (Ex. Airfoil) In Bluff bodies: pressure Drag > Friction Drag. po A =< Ene — _— . Streamlined body ae Bluff Body 91, For —hydro-dynamically smooth boundary, the friction coefficient for turbulent flow is {a) Constant {b) Dependent only on Reynolds number {c) A function of Reynolds number and relative roughness (d) Dependent on relative roughness only Sol. (b) Friction coefficient value: 16 Laminar flow 2 (R, < 2000) 0.079 Turbulent Flow = “Piz- (Re = 4000 to 10°) 92. The value of friction factor ‘f for smooth pipes for Reynolds number 10° is approximately equal to (a) 0.2 {b) 0.01 (c) 0.001 (4) 0.0001 Sol. (b) Re = 10° (Turbulent flow) 0.316 (ay Friction factor f= 0.316 = Gone 93. For laminar flow in a pipe of circular cross-section, the Darcy's friction factor fis (a) Directly proportional to Reynolds number and independent of pipe wall roughness OO Engineer's Pride wy nan eves jon Rabe GHAND SR | Crone Aaress 25 Giesh Marg. € Back Mahesh Rag ‘aha, Sonal Pra Made (between Gandhi Maar Ralway Salon and Ours Pura Raway Stn, Soe, Roshan, SIGNS, TOLeH2OG,eOveOTaL? 30 | 600{b) Directly proportional to pipe wall roughness and independent of Reynolds number {c) Inversely proportional to Reynolds number and independent of pipe wall roughness (d) Inversely proportional to Reynolds number and directly proportional to pipe wall roughness Sol. (c) Loss of head due to friction AV? 2ad For laminar flow r-(¥) 2 n,-( 4 )2 R, ) 2d and hy is independent of wall roughness 94. Separation of flow occurs when (a) The pressure intensity reaches a minimum (b) The cross-section of a channel is reduced {c) The boundary layer comes to rest (d) All of the above Sol, (c) The fluid layer adjacent to the solid surface has to do work against surface friction by consuming some kinetic energy. The loss of kinetic energy recovered from adjacent fluid layer through momentum exchange process. Along the length of solid body at which the boundary layer is on the limit of separation from the surface is called point of separation. 95. The loss of energy due to sudden enlargement is given by Engineer's Je oy an 15 nanan (c) h 4) where Au, Vi are area of cross-section and velocity at entry and A2, V2, are area of cross-section and velocity at exi Sol. (a) Loss of head due to sudden enlargement =a 96. The ratio of average velocity to maximum velocity for steady, laminar flow in circular pipes is fa) 1/2 (b) 2/3 (c) 3/2 (a) 2 Sol. (a) Velocity distribution for laminar flow in pipe UF Unar @ r= 0 lap 4u x Twa) copl Pus Mode (hetwcen Gon Nagar Rainy Seton and Durga Pura RatmeyStavon, Jap, Aashan, SESORDTI<, 7OLeN208%2, @O78C7812 31 | 60097. The distance from pipe boundary, at which the turbulent shear stress is one- third the wall shear stress, is (a) 1/3R (b)- 1/2R (c) 2/3R (d) 3/4R Where R is the radius of pipe. Sol. (c) 98. The discharge of a liquid of kinematic viscosity 4 cm?/sec through a 8 cm dia- meter pipe is 32007 cm/sec. The type of flow expected is (a) Laminar flow (b) Transition flow {c) Turbulent flow (d) Not predictable from the given data Sol. (a) Engineer's Pride pyran aiesina Reynold number R, Here V Q A R, -(2)-2 320078 _ 409 < 2000 a axe x4 Since Re < 2000 => laminar flow. 99, The Prandtl! mixing length is (a) Zero at the pipe wall (b) Maximum at the pipe wall (c) Indepéfident of shear stress (a)Noné of the above Sol: (a) Prandtl’s mixing length theory is a 2-D model attempting to describe the momentum. transfer within a turbulent fluid flow. Defined as the average distance that a small mass of fluid will travel before it exchanges its momentum with another mass of fluid. 100. The velocity distribution for laminar flow through a circular tube {a) Is constant over the cross-section {b) Varies linearly from zero at walls to maximum at centre (c) Varies parabolically with maximum at the centre (d) None of the above Sol. (c) Velocity distribution in circular pipe for laminar flow alfa 2 a(Z)e-") 4u\ ae 101. A fluid of kinematic viscosity 0.4 cm?/sec flows through a 8 cm diameter pipe. The maximum velocity for laminar flow will be ays -BCHANO S| Csseom/OfieeAdres-225,Ganen Mare. Back Maho aga [200 Wet om RAB Sah Page 32 | 600(a) Less than 1 m/sec (b) 1 m/sec (c) 1.5 m/sec (d) 2 m/sec Sol. (b) Given L = 0.4 cm’/s = 0.4 *10“m?/s D=8cm=0.08m For laminar flow (Remax = 2000 (Redan = 2000 = ( 222 } L vy = 2000x0410" = 0.08 Vian = lm/ sec 102. The losses are more in (a) Laminar flow (b) Transition flow {c) Turbulent flow (d) Critical flow y, Sol. (c) Since velocity Yurbwlan 7 Yiaminar and major head losses are due to friction for 2gd 64 and f/ =— (laminar flow) where R, = -_ 16 f=—e oli, pyD For Turbulant flow 79 x4 = hav Hence (h,) ter” (sa 103. The wake (a) Always occurs before a separation point {b) Always occurs after a separation point (c) sa region of high-pressure intensity (d) None of the above Sol. (b) _. —— — ))) NO formation Along the length of the solid body, at a certain point. when the boundary layer may not be able to keep sticking to the solid body. In other words, the boundary layer will be separated from the surface Hence wake formation occurs after a separation point. 104. The maximum thickness of boundary layer ina pipe of radius ris (a) 0 (b) r/2 (or (a) 2r Sol. (c) In pipe flow, where boundary layer thickness equal to radius of pipe. Fully Entrance Developed Region Region Boundary Layer Engineer's Pride sy stone es nion tay, BCHANDGA | Cauoun/Otes Aas C225, Goes Nar Coe, Mahesh agar {20D Meter om urs Mode Uctwcen Gowen Nagar Ralway Saton ard. Deh Ara Ray Staton), Jopw, Roshan, S66O47Le, 70320833, aO7AO7EI2 33 | 600105. The hydraulic grade line is (a) Always above the centre line of pipe (b) Never above the energy grade line (c) Always sloping downward in the direction of flow (A) All of the above Sol. (b) Hydraulic gradient line (HGL): - Sum of pressure head (4) and datum head (2) of Ps flowing fluid in a pipe wrt some reference jine Total energy line (TEL): - Pressure head + datum head + kinetic head so HGL can never above TEL. 106. Two pipe systems are said to be equivalent when (a) head loss and discharge are same in two systems (b) length of pipe and discharge are same in two systems (0) friction factor and length are same in, two systems (d) length and diameter are same in two. systems [cs.93] Sol. (a) Two pipe systems are said to be equivalent when head lass and discharge are same in two systems. Eq lent pipe is a method of reducing a combination of pipes into a simple pipe system for easier analysis of a pipe network, such as a water distribution system. An equivalent pipe is an imaginary pipe in which the head loss and discharge are equivalent to the head loss and discharge for the real pipe system. There are three main properties of a pipe: diameter, length, and roughness. As the coefficient of roughness, C, decreases the roughness of the pipe decreases. For example, a new smooth pipe has a roughness factor of C = 140, while a rough pipe is usually at C = 100. To determine an equivalent pipe, you must assume any of the above two properties. Therefore, for a system of pipes with different diameters, lengths, and roughness factors, you could assume a specific roughness factor (most commonly C = 100) and diameter (most commonly D = 8"). The most common formula for computing equivalent pipe is the Hazen- Williams formula. 107. Inseries-pipe problems (a) The head loss is same through each pipe (b) The discharge is same through each pipe (€) Atrial solution is not necessary (d) The discharge through each pipe is added to obtain total discharge Sol. (b) fF LE The pipes of different length and different diameters connected end to end (in series) to form a pipe line. Discharge is same through each pipe Q= AV, = AV, = AN, 108. Select the correct statement. (a) The absolute roughness of a pipe de- creases with time. (b) A pipe becomes smooth after using for long time. (c) The friction factor decreases with time. {d) The absolute roughness increases with time, Sol. (d) —_— sa Engineer's fe oy-an 16min falinays-@CHANDSIR| Cl Move (tween Ganchs Nagar indy Staton and Dur Fur Radway Sin, lr, Athan,SEGRO7IO. 7LLS2O8S. 7eE07012 34 | 600© Absolute roughness of pipe decreases with time. © Apipe becomes rough after using for long time. © The friction factor increases with time. 109. A valve is suddenly closed in a water main in which the velocity is1 m/sec and velocity of pressure wave is 981 m/sec. ‘The inertia head at the valve will be {a)1m (b) 10m (c) 100m (d) none of the above Sol. (c) For sudden closure of value Inertia head at value _ ev _981x1 ‘g 981 110. The speed of a pressure wave through a pipe depends upon =100m (a) The length of pipe (b) The viscosity of fluid t {c) The bulk modulus for the fluid (d) The original head Sol. (¢) For sudden closure of value at pipe (i) Rigi P 1D +2 ko Et Here K is bulk modulus of elasticity. (ii) Elastic p =v 111. If the speed of pressure wave is vo and pipe length is L, rapid closure occurs when time of closure is (a) Less than = (b) Greater than = (c) Less than = (d) Zero Sol. (a) Time of closure- time taken by pressure wave to travel from the valve to the tank and from tank to valve. Total Distance = (L+L)=2L ae ( Distance ) 2L velocity of pressure valve, Gradual closure tt > 2% c Sudden closure if < 2 ¢ 112. When time of closure te =L/vo (where L is length of pipe and vo is speed of pressure wave), the portion of pipe length subjected to maximum head is. (a) Wa (o) 3 (ue (ae Sol. (c) Length of pipe subjected to maximum head 7 jis 2 pe 2 “Vo ae 2 113. If the elevation of hydraulic grade line at the junction of three pipes is above the elevation of reservoirs B and C and below reservoir A, then the direction of flow will be {a) From reservoir A to reservoirs B and c (b) From reservoir B to reservoirs C and A Engineer's ran &1ES dn falas BCHANDSIR | Chsro/OMce Aeres.c205, Ganesh Marg Cua, Maesh Nags (20D Meteo Rd SA Twat, Gopal Pra Nace ectacen Cah Nag Rooney Staton and Durga Pura Rata Sao), Jn, Ratan, SEGDSTI,7LS22083, SO7RCOTEL2 © 35 | 600(c) From reservoir C to reservoirs Aand B (d) Unpredictable Sol. (a) HGL ~ Given sum of pressure head (2) and datum head (2) of a flowing fluid in sg a pipe w.r.t. some reference line. (b) TEL — (pressure head + Datum Head + Kinetic Head) 114, If there are n pipes of same diameter d laid in parallel in place of a single pipe of diameter D, then (a) d=; (b) D= () d=35 Sol. (a) For flow through parallel pipes (a) O= ,+0,,---@, AV= AV, + AV, +~ 4 4 DV =nd?9 sD age ll (b) Head loss for each Branch pipe is same. LV? _ fLS? 2gd — 2ed 2 pw =24y, +2 av, +---2a’v, ao" a ) 115. The length of a pipe is 1 km and its diameter is 20 cm. If the diameter of an equivalent pipe is 40 cm, then its length is Engineer's Pride oy rane s,inaann “rat, Gopal Ps Mase between Gone Nagar (a) 32 km (b) 20 km ()8km (4) 4km Sol. (a) Equivalent Pipe: - is the pipe of uniform diameter having loss of head and discharge equal to the loss of head and discharge of a compound pipe. Head loss inn compound pipe = equivalent pipe (20) (40) & L = 32km| 116. Two pipes of same length and diameters d and 2d respectively are connected in series. The diameter of an equivalent pipe of same length is (a) Less than d (b) Between dand1.5d (c) Between 1.5 d and 2d (d) Greater than 2d Sol, (a) Flow through pipes in series AV D; D>; 36 | 600= [Ded 117. The horsepower transmitted through a pipe is maximum when the ratio of loss of head due to friction and total head supplied is (a) 1/3 (b) 1/4 () 1/2 (a) 2/3 Sol. (a) Let initial head is H Head available at outlet (H-hi) Power transmitted p= gO(H-h,) Since h, a Q=4V gi = pgd| Mi ? osa| te fe For maximum power transmission Engineer's Pride oy snona cs idan alway, @CHANOSR | Catsrom/Ofe Atdess 25, Ganesh Marg. lok Maes) No 200 Me 118. The boundary layer thickness at a distance of 1 m from the leading edge of a flat plate, kept at zero angle of incidence to the flow direction, is 0.1 cm. The velocity outside the boundary layer is 25 m/ sec, the boundary layer thickness at a distance of 4 mis (a) 0.40 cm (b) 0.20 cm {c)0.10 om (4) 0.05 cm Assume that boundary layer is entirely laminar. Sol. (b) For laminar boundary layer 6 a VX 5,=0:lém, x, =Im 3,22 x, =4m E = [s, = 0.2cm| s, V4 119. Drag force is a function of > (i) Projected area of the body Mass density of the fluid i The correct answer is (a) (i)and (i) (b) Gi) and (ii) (c) (il) ana (it) (4) (i), (i) ane (ii) Velocity of the body Sol. (d) *-" Drag Force Fo = copa ve [P= sleAv] 120. The correct relationship among displacement thickness d, momentum thickness m and energy thickness e is (a) d>m>e (b)d>e>m ()pd>m Sol. (d) Tih copa Pos Mode (eetren GandN Naar Raley Staton and Ours Pa Ralway Statin, pur, jan, SECRETS, 70242080, P7ECO7E © 37 | 600Displacement thickness (s/or w= f(-2)o Momentum thickness (@) or n-f4(-S}o 2U\ Energy thickness (s) or e = le>d>m!| 121. For laminar flow in circular pipes, the Darcy's friction factor Fis equal to (a) 16/Re (b) 32/ Re (0) 64/ Re (d) None of the above where Re is Reynolds number. Sol. (c) For laminar flow through pipe, Darcy's is friction factor Where Re = Reynold’s number = (2) u 122. Surge wave in a rectangular channel is an example of (i) Steady flow (ii) Unsteady flow i) Uniform flow (iv) Non-uniform flow The correct answer is (a) (i) and (ii) {c) (i) and (iv) (b) (ii) and (iii) (d) (ii) and (iv) Sol. (d) Surge - sudden power full forward/upward movement Unsteady flow: - flow parameters i.e. velocity, pressure or density changes w.r.t. time. Non-Uniform flow: - In which flow parameters changes with space. 123, The best hydraulic channel cross- section is the one which has a (a) Minimum roughness coefficient (b) Least cost (c) Maximum area for a given flow (d) Minimum wetted perimeter Sol. (d) For most economical and efficient sections: - © Cost. of “construction of channel is minimum. @ Have maximum discharge with minimum, perimeter for given cross sectional area. 124, Which is the best hydraulic section of the following open channel cross- sections? {a) Rectangle (b) Triangle {c) Trapezoidal (d) Semi-circle Sol. (b) Since semicircle section gives maximum discharge with minimum perimeter for a given cross sectional area hence it is best hydraulic section. 125. Hydraulic jump is a (i) Steady flow (ii) Uniform flow (iii) Unsteady flow (iv) Non-uniform flow The correct answer is (a) (i) and (ii) (b) (i) and (iv) (c) (ii) and (ii) (d) (iii) and (iv) 38 | 600Sol. (b) Hydraulic Jump is sudden rise of depth of water in d/s w.r.t. u/s when flow changes from super critical condition to subcritical condition. In hydraulic Jump flow remains steady and non-uniform. 126. The hydraulic jump always occurs from (a) Below critical depth to above critical depth (b) Above critical depth to below critical depth (c) Below critical depth to above normal depth (d)Above normal depth to below normal depth Sol. (a) Hydraulic Jump occurs when flow changes from supercritical to subcritical condition. Supercritical flow y < yc (Below critical Depth) Subcritical flow y > yc (Above critical Depth) Supercritical ! 'Suberiteal Flow 1 Hydraulic Flow (Fry> 1) Sump (Fn<1) 127. Ima gradually varied flow {a) The slopes of energy grade line, hydraulic grade line and bottom of the channel are same (b) The slopes of energy grade line and hydraulic grade line are same but slope of the bottom of channel is different (c) The slopes of hydraulic grade line and bottom of channel are same, but slope of energy grade line is different (a) The slope of energy grade line, hydraulic grade line and bottom of channel are all different. Sol. (d) In GVF due to non-uniform flow for a given length of the channel, the velocity of flow, depth of flow etc. Do not remain constant, so slope of EGL, HGL and bottom of channel are all different. 128. The flow in channels is considered to be in transitional state if the Reynolds number is (a) Less than 500 (b) Between 500 and 2000 (c) Between 2000 and 4000 (d) Greater than 4000 Sol. (b) For flow in open channels R, £500 = laminar flow 500 Turbulent flow 129. The Froude number is defined as Vv gD where v is the mean velocity of flow, g is acceleration due to gravity and Dis {a) Depth of flow (b) Hydraulic depth (c) Hydraulic mean depth (d) All of the above Sol. (b) Froude number f- Jo D = Hydraulic Depth Engine Toh, Gop fara Mode be ‘Tan BLES fan Atay BCHANDSIR | CisromyOM cove 22, Ganev, Calc, Mave Nagy (200 Meter om Rs | 39 | 600wetted area A ‘op width of channel 130. For shooting flow, the Froude number is (a) Zero (b) Less than one (c) Less than two. (d) Greater than one Sol. (d) For subcritical /tranquil/ streaming flow F, <1 For critical flow Fr= 1 For supercritical/ shouting / rapid / torrential Fa 131. For uniform flow in a channel {a) The total energy line, water sur‘ace and bottom of channel are all horizontal {b)The total energy line and water surface are horizontal, but bot:om of channel is inclined (c) The total energy line, hydreulic gradient line and bottom of channel are all parallel (d)Water surface and bottom of channel are parallel to each other, but energy grade fine is not parallel to then Sol. (¢) For uniform flow in open channel water depth y, flow area A, discharge Q and velocity distribution V at all sections throughout entire channel must remain constant. The slope of energy cine gradient (s.), water surface slope (sus) and the channel bed slope (sc) are equal. 132. The Chezy's coefficient (a) Is dimensionless (b) Has the dimension of velocity (c) Has the dimension of discharge (d) Has the dimension U2 T Sol. (d) Chezy's formula for open channels v = e vee ee 1c2 = Vmi JRs ¢ bat as Aya ox JE \p Vv easier 133. If “f is the friction factor, then the Chezy's coefficient is proportional to (a) f (b) JF 1 1 (oz ay 8 Sol. (d) Since chezy’s constant C= a Where fis friction factor. 134. The relationship between Manning's coefficient n and Chezy's coefficient ¢ (coe (dec Where Ris the hydra mean depth. Sol. (b) Since chezy’s formula for velocity v = EARS covsnonenrsne (2) — Engines 40 | 600And Manning's Formula for velocity v = 1 Regi -.(2) n U: c sing equations (1) & (2) RN on 135, The depth of flow for maximum velocity in a circular channel section with diameter equal to 1.5 mis (a) 0.75m (b)1.065m_ {c) 1.215m (d) 1.425m, Sol. (c) For circular open channel depth of flow for maximum velocity is d= 0.81 D D = dia. of channel Here D = 1.5m So, Depth d= 0.81 "4.5 d =1.215m 136. For maximum discharge in a circular channel section, the ratio of the depth of flow to that of diameter of the channel {a) 0.30 (b).0.50 {c) 0.81 (a) 0.95 Sol. (d) For maximum discharge in circular d open channel 95] (condition for most efficient section) 137. A triangular channel section is most economical when each of its sloping sides is inclined to the vertical at an angle of (a) 30° (b) 45° (c) 60° (a) 75° Sol. (b) Most efficient triangular channel: 2my ee my my A= My P= 2yvltm or P= 2VA,]m-+ for most efficient channel (¢ m=1 o=45° 138, For a trapezoidal channel section to be most economical, its hydraulic radius must be equal to (a) > (o) > On @ 35 Where y is the depth of flow. Sol. (b) Most efficient trapezoidal channel (b+2nd) Hydraulic Radius R =4 P A= Area=(b+nd)d Perimeter P = b + (b + 2nd) So hydraulic radius |R Ad P_2 'S Pride oyun a5 nda Rina BCHAND S| CssoonvOtice Ades: 41 | 600139. The critical state of flow through a channel section may be defined as the state of flow at which the (a) Specific energy is maximum for a given discharge (b) Specific force is maximum for a given discharge (c) Discharge is maximum for a given specific force o le (d) Discharge is minimum for a given specific energy Sol. (c) Condition for critical flow: - (i) For a given discharge, specific energy and specific force are minimum. (li) For a given specific energy or specific force discharge is maximum. (ili) Fr= a. (iv) Velocity Hea 1 = 7 Hydraulic depth 140. The critical state of flow in a non- rectangular channel is expressed by 2X (¢) oy 2 Tr fa) g g ow OA QA g@lA oF (a= as 1¢596] Sol. (b) The critical state of flow in a non- rectangular channel is expressed by: er gAs g A g oT 141, The critical depth of flow in a most economical triangular channel section for a discharge of 1 m?/sec is given by Sol. (c) 142. For a given specific energy E, the critical depth y., for a rectangular channel is given by (a) {c) [BCHANDSICasroon/Otice Aaare.C225, Gane Mars Clk, Maer nga f00 Meter ron Rad SEN 42 | 600