# Civil Engineering Important MCQ | Hydraulics And Fluid Mechanics Part 3

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## Hydraulics And Fluid Mechanics Part 3

201. The flow in which the velocity vector is identical in magnitude and direction at
every point, for any given instant, is known as

(a) one dimensional flow
(b) uniform flow
(d) turbulent flow
(e) streamline flow.

Ans: b

202. The flow in which the particles of a fluid attain such velocities that vary from
point to point in magnitude and direction as well as from instant to instant,
is known as

(a) one dimensional flow
(b) uniform flow
(d) turbulent flow
(e) streamline flow.

Ans: d

210. Flow
occurring in a pipeline when a valve is being opened is

(c) laminar
(d) vortex
(e) rotational.

Ans: b

211. General energy equation holds for

(b) turbulent flow
(c) laminar flow
(d) non-uniform flow
(e) all of the above.

Ans: d

212. A streamline is defined as the line

(a) parallel to central axis flow
(b) parallel to the outer surface of pipe
(c) of equal yelocity in a flow
(d) along which the pressure drop is uniform
(e) which occurs in all flows.

Ans: c

213. Two dimensional flow occurs when

(a) the direction and magnitude of the velocity at all points are identical
(b) the velocity of successive fluid particles, at any point, is the same at
successive periods of time
(c) the magnitude and direction of the velocity do not change from point to
point in the fluid
(d) the fluid particles move in plane or parallel planes and the streamline
patterns are identical in each plane
(e) velocity, depth, pressure, etc. change from point to point in the fluid
flow.

Ans: d

## 215. A piece of metal of specific gravity 7 floats in mercury of specific gravity 13.6. What fraction of its volume is under mercury?

(a) 0.5
(b) 0.4
(c) 0.515
(d) 0.5
(e) none of the above.

Ans: c

216. A piece of wood having weight 5 kg floats in water with 60% of its volume under
the liquid. The specific gravity of wood is
(a) 0.83
(b) 0.6
(c) 0.4
(d) 0.3
(e) none of the above.

Ans: b

21 The velocity of jet of water travelling out of opening in a tank filled with water
is proportional to

(b) h2
(c) V/T
(d) h2
(e) h3/1.

Ans: c

219. In a
free vortex motion, the radial component of velocity everywhere is
(a) maximum
(b) minimum
(c) zero
(d) non-zero and finite
(e) unpredictable.

Ans: c

220. In a
forced vortex, the velocity of flow everywhere within the fluid is
(a) maximum
(b) minimum
(c) zero
(d) non-zero finite
(e) unpredictable.

Ans: d

221. The
region between the separation streamline and the boundary surface of the solid
body is known as
(a) wake
(b) drag
(c) lift
(d) boundary layer
(e) aerofoil section.

Ans: a

222. For
hypersonic flow, the Mach number is
(a) unity
(b) greater than unity
(c) greater than 2
(d) greater than 4
(e) greater than 10.

Ans: d

223. The
upper surface of a weir over which water flows is known is
(a) crest
(b) nappe
(c) sill
(d) weir top
(e) contracta.

Ans: c

224.
Normal depth in open channel flow is the depth of flow corresponding to
(c) laminar flow
(d) uniform flow
(e) critical flow.

Ans: d

226.
Uniform flow occurs when
(a) the direction and magnitude of the velocity at all points are identical
(b) the velocity of successive fluid pai-ticles, at any point, is the same at
sucÂ¬cessive periods of time
(c) the magnitude and direction of the velocity do not change from point to
point in the fluid
(d) the fluid particles move in plane or parallel planes and the streamline
pat-terns are identical in each plsr.e
(e) velocity, depth, pressure, etc. change from point to point in the fluid
flow.

Ans: c

227. Pitot
tube is used for measurement of
(a) pressure
(b) flow
(c) velocity
(d) dsscharge
(e) viscosity.

Ans: c

22
Hydrometer is used to determine
(a) specific gravity of liquids
(b) specific gravity of solids
(c) specific gravity of gases
(d) relative humidity
(e) density.

Ans: a

229. The
total energy of each particle at various places in the case of perfect
incompres sible fluid flowing in continuous sream
(d) keeps on increasing
(b) keeps on decreasing
(c) remains constant
(d) may increase/decrease
(e) unpredictable.

Ans: c

230.
According to Bernoulliâ€™s equation for steady ideal fluid flow
(a) principle of conservation of mass holds
(b) velocity and pressure are inversely proportional
(c) total energy is constant throughout
(d) the energy is constant along a stream-line but may vary across streamlines
(e) none of the above.

Ans: d

231. The
equation of continuity holds good when the flow
(b) is one dimensional
(c) velocity is uniform at all the cross sec-tions
(d) all of the above
(e) none of the above.

Ans: d

232. Mach
number is significant in
(a) supersonics, as with projectiles and jet propulsion
(b) full immersion or completely enclosed flow, as with pipes, aircraft wings,
nozzles etc.
(c) simultaneous motion through two fluids where there is a surface of
dis-continuity, gravity force, and wave making effects, as with shipâ€™s hulls
(d) all of fhe above
(e) none of the above.

Ans: a

233.
Froude number is significant in
(a) supersonics, as with projectile and jet propulsion
(b) full immersion or completely enclosed flow, as with pipes, aircraft wings,
nozzles etc.
(c) simultaneous motion through two fluids where there is a surface of
dis-continuity, gravity forces, and wave making effect, as with shipâ€™s hulls
(d) all of the above
(e) none of the above

Ans: c

234. All
the terms of energy in Bernoulliâ€™s equation have dimension of
(a) energy
(b) work
(c) mass
(d) length
(e) time.

Ans: d

235.
Reynolds number is significant in
(a) supersonics, as with projectile and jet propulsion
(b) full immersion or completely enclosed flow, as with pipes, aircraft wings,
nozzles etc.
(c) simultaneous motion through two fluids where there is a surface of
dis-continuity, gravity forces, and wave making effect, as with shipâ€™s hulls
(d) all of the above
(e) none of the above.

Ans: b

236. The
fluid forces considered in the Navier Stokes equation are
(a) gravity, pressure and viscous
(b) gravity, pressure and turbulent
(c) pressure, viscous and turbulent
(d) gravity, viscous and turbulent
(e) none of the above.

Ans: a

237. A
large Roynold number is indication of
(a) smooth and streamline flow
(b) laminar flow
(d) turbulent flow
(e) highly turbulent flow.

Ans: e

239. For
pipes, laminar flow occurs when Roynolds number is
(a) less than 2000
(b) between 2000 and 4000
(c) more than 4000
(d) less than 4000
(e) none of the above.

Ans: a

240. In
order that flow takes place between two points in a pipeline, the differential
pressure between thes^ points must be more than
(a) frictional force
(b) viscosity
(c) surface friction
(d) all of the above
(e) none of the above.

Ans: d

241. At
the centre line of a pipe flowing under pressure where the velocity gradient is
zero, the shear stress will be
(a) minimum
(b) maximum
(c) zero
(d) negative value
(e) could be any value.

Ans: e

242. The
pressure in Pascals at a depth of 1 m below the free surface of a body of water
will be equal to
(a) 1 Pa
(b) 91Pa
(c) 981 Pa
(d) 9810 Pa
(e) 98,100 Pa.

Ans: d

244. Two
pipe systems can be said to be equivalent, when the following quantites are same
(a) friction loss and flow
(b) length and diameter
(c) flow and length
(d) friction factor and diameter
(e) velocity and diameter.

Ans: a

245. For
pipes, turbulent flow occurs when Reynolds number is
(a) less than 2000
(b) between 2000 and 4000
(c). more than 4000
(d) less than 4000
(e) none of the above.

Ans: c

246.
Bernoulli equation deals with the law of conservation of
(a) mass
(b) momentum
(c) energy
(d) work
(e) force.

Ans: c

247. A

hydraulic press has a ram of 15 cm diameter and plunger of 1.5 cm. It is
required to lift a weight of 1 tonne. The force required on plunger is equal tc
(a) 10 kg
(b) 100 kg
(c) 1000 kg
(d) 1 kg
(e) 10,000 kg.

Ans: a

24
Cavitation is caused by
(a) high velocity
(b) high pressure
(c) weak material
(d) low pressure
(e) low viscosity.

Ans: d

249. Cavitation will begin when
(a) the pressure at any location reaches an absolute pressure equal to the
saturated vapour pressure of the liquid
(b) pressure becomes more than critical pressure
(c) flow is increased
(d) pressure is increased
(e) none of the above.

Ans: a

250.
Principle of similitude forms the basis of
(a) comparing two identical equipment
(b) designing models so that the result can be converted to prototypes
(c) comparing the similarity between design and actual equipment
(d) hydraulic designs
(e) performing acceptance tests.

Ans: b

251. For
similarity, in addition to models being geometrically similar to prototype, the
following in both cases should also be equal
(a) ratio of inertial force to force due to viscosity
(b) ratio of inertial force to force due to gravitation
(c) ratio of inertial force to force due to surface tension
(d) all the four ratios of inertial force to force due to viscosity,
gravitation, surface tension, and elasticity

Ans: d