# Civil Engineering Important MCQ PDF-Hydraulics And Fluid Mechanics Part 2

101.
Capillary action is due to the
(a) surface tension
(b) cohesion of the liquid
(c) adhesion of the liquid molecules and the molecules on the surface of a
solid
(d) all of the above
(e) none of the above.
Ans: d

103.
Newton’s law of viscosity is a relationship between
(a) shear stress anctthejiate of angular distortion
(b) shear stress and viscosity
(c) shear stress, velocity and viscosity
(d) pressure, velocity and viscosity
(e) shear stress, pressure and rate of angular distortion.
Ans: a

104. The
atmospheric pressure with rise in altitude decreases
(a) linearly
(b) first slowly and then steeply
(c) first steeply and then gradually
(d) unpredictable
(e) none of the above.
Ans: b

105.
Pressure of the order of 10″‘ torr can be measured by
(a) Bourdon tube
(b) Pirani Gauge
(c) micro-manometer
(d) ionisastion gauge
(e) McLeod gauge.
Ans: d

106.
Operation of McLeod gauge used for low pressure measurement is based on the
principle of
(a) gas law
(b) Boyle’s law
(c) Charle’s law
(d) Pascal’s law
(e) McLeod’s law.
Ans: b

107. An
odd shaped body weighing 7.5 kg and occupying 0.01 m3 volume will be completely
submerged in a fluid having
specific gravity of
(a) 1
(b) 1.2
(c) 0.8
(d) 0.75
(e) 1.25.
Ans: d

10 In an
isothermal atmosphere, the pressure
(a) decreases linearly with elevation
(b) remains constant
(c) varies in the same way as the density
(d) increases exponentially with elevation
(e) unpredictable.
Ans: c

109.
Mercury is often used in barometer because
(a) it is the best liquid
(b) the height of barometer will be less
(c) its vapour pressure is so low that it may be neglected
(d) both (b) and (c)
(e) it moves easily.
Ans: d

110.
Barometer is used to measure
(a) pressure in pipes, channels etc.
(b) atmospheric pressure
(c) very low pressure
(d) difference of pressure between two points
(e) rain level.
Ans: b

111. Which
of the following instrument can be used for measuring speed of a submarine
moving in deep sea
(a) Venturimeter
(b) Orifice plate
(c) hot wire anemometer
(d) rotameter
(e) pitot tube.
Ans: e

112. Which
of the following instrument can be used for measuring speed of an aeroplane
(a) Venturimeter
(b) Orifice plate
(c) hot wire anemometer
(d) rotameter
(e) pitot tube.
Ans: e

113.
Piezometer is used to measure
(a) pressure in pipe, channels etc.
(b) atmospheric pressure
(c) very low pressures
(d) difference of pressure between two points
(e) flow.
Ans: c

114. Which
of the following instruments is used to measure flow on the application of
Bernoulli’s theorem
(a) Venturimeter
(b) Orifice plate
(c) nozzle
(d) pitot tube
(e) all of the above.
Ans: e

116. The
speed of sound in a ideal gas varies directly as its
(a) pressure
(b) temperature
(c) density
(d) modulus of elasticity
(e) absolute temperature,
Ans: e

119.
Dynamic viscosity of most of the liquids with rise in temperature
(a) increases
(b) decreases
(a) remains unaffected
(d) unpredictable
(e) none of the above.
Ans: b

120.
Dynamic viscosity of most of the gases with rise in temperature
(a) increases
(b) decreases
(c) remains unaffected
(d) unpredictable
(e) none of the above.
Ans: a

121. A
metal with specific gravity of o floating in a fluid of same specific gravity a
will
(a) sink to bottom
(b) float over fluid
(c) partly immersed
(d) be fully immersed with top surface at fluid surface
(e) none of the above.
Ans: d

123.
Euler’s dimensionless number relates the following
(a) inertial force and gravity
(b) viscous force and inertial force
(c) viscous force and buoyancy force
(d) pressure force and inertial force
(e) pressure force and viscous force.
Ans: d

12
Manometer is used to measure
(a) pressure in pipes, channels etc.
(b) atmospheric pressure
(c) very low pressure
(d) difference of pressure between two points
(e) velocity.
Ans: a

.129.
Which of the following manometer has highest sensitivity
(a) U-tube with water
(b) inclined U-tube
(c) U-tube with mercury
(d) micro-manometer with water
(e) displacement type.
Ans: d

130. In
order to increase sensitivity of U-tube manometer, one leg is usually inclined
by angle 9. Sensitivity of inclined tube to sensitivity of U-tube is equal to
(a) sin 9
(b) sin 9
(c) casS
(d) cos 9
(e) tan 9.
Ans: b

131.
Working principle of dead weight pressure gauge tester is based on
(a) Pascal’s law
(b) Dalton’s law of partial pressure
(c) Newton’s law of viscosity .
(e) Second law of thermodynamic.
Ans: a

132. The
resultant of all normal pressures acts
(a) at e.g. of body
(b) at center of pressure
(c) vertically upwards
(d) at metacentre
(e) vertically downwards.
Ans: c

133.
Centre of pressure compared to e.g. is
(a) above it
(b) below it.
(c) at same point
(d) above or below depending on area of body
(e) none of the above.
Ans: b

134.
Metacentric height is the distance between the metacentre and
(a) water surface
(b) center of pressure
(c) center of gravity
(d) center of buoyancy
(e) none of the above.
Ans: c

135.. The
resultant upward pressure of the fluid on an immersed body due to its tendency
to uplift the sub-merged body is called
(a) upthrust
(b) reaction
(c) buoyancy
(d) metacentre
(e) center of pressure.
Ans: c

136. The
center of pressure of a surface subjected to fluid pressure is the point
(a) on the surface at which resultant pres-sure acts
(b) on the surface at which gravitational force acis
(c) at which all hydraulic forces meet
(d) similar to metacentre
(e) where pressure equivalent to hydraulic thrust will act.
Ans: a

137.
Buoyant force is
(a) the resultant force acting on a floating body
(b) the resultant force on a body due to the fluid surrounding it
(c) equal to the volume of liquid dis-placed
(d) the force necessary to maintain equilibrium of a submerged body
(e) none of the above.
Ans: b

138 The
horizontal component of buoyant force is
(a) negligible
(b) same as buoyant force
(c) zero
Ans: c

140. The
line of action of the buoyant force acts through the
(a) centroid of the volume of fluid vertically above the body
(b) center of the volume of floating body
(c) center of gravity of any submerged body
(d) centriod of the displaced volume of fluid
(e) none of the above.
Ans: d

141.
Center of buoyancy is the
(a) centroid of the displaced volume of fluid
(b) center of pressure of displaced volume
(c) e.g. of floating ‘body
(d) does not exist
(e) none of the above.
Ans: a

142. A
body floats in stable equilibrium
(a) when its meatcentric height is zero
(b) when the metancentre is above e.g.
(c) when its e.g. is below it’s center of buoyancy
(d) metacentre has nothing to do with position of e.g. for determining
stability
(e) none of the above.
Ans: b

l43. A
piece weighing 3 kg in air was found to weigh 2.5 kg when submerged in water.
Its specific gravity is
(a) 1
(b) 5
(c) 7
(d) 6
Ans: d

151. The
total pressure force on a plane area is equal to the area multiplied by the
intensity of pressure at the centriod, if
(a) the area is horizontal
(b) the area is vertical
(c) the area is inclined
(d) all of the above
(e) none of the above.
Ans: d

152. A
square surface 3 m x 3 m lies in a vertical line in water pipe its upper edge
at vater surface. The hydrostatic force on square surface is
(a) 9,000 kg
(b) 13,500 kg
(c) 18,000 kg
(d) 27,000 kg
(e) 30,000 kg.
Ans: b

153. The
depth of the center of pressure on a vertical rectangular gate 8 m wide and 6 m
high, when the water surface coincides with the top of the gate, is
(a) 2.4 m
(b) 3.0 m
(c) 4.0 m
(d)”2.5 m
(e) 5.0 m.
Ans: b

154. If
the atmospheric pressure on the surface of an oil tank (sp. gr. 0.8) is 0.2
kg/cm”, the pressure at a depth of 50 m below the oil surface will be
(a) 2 meters of water column
(b) 3 meters of water column
(c) 5 meters of water column
(d) 6 meters of water Column
(e) 7 meters of water column.
Ans: d

155.
Metacentre is the point of intersection of
(a) vertical upward force through e.g. of body and center line of body
(b) buoyant force and the center line of body
(c) mid point between e.g. and center of buoyancy
(d) all of the above
(e) none of the above.
Ans: b

156.
Choose the wrong statement
(a) The horizontal component of the hydro-static force on any surface is equal
to the normal force on the vertical projection of the surface
(b) The horizontal component acts through the center of pressure for the
vertical projection
(c) The vertical component of the hydrostatic force on any surface is equal to
the weight of the volume of the liquid above the area
(d) he vertical component passes through the center of pressure of the volume
(e) Center of pressure acts at a greater depth than center of gravity.
Ans: d

157. For a
body floating in a liquid the normal pressure exerted by the liquid acts at
(a) bottom surface of the body
(b) e.g. of the body
(c) metacentre
(d) all points on the surface of the body
(e) all of the above.
Ans: d

15 Choose
the wrong statement
(a) any weight, floating or immersed in a liquid, is acted upon by a buoyant
force
(p) Buoyant force is equal to the weight of the liquid displaced
(c) The point through which buoyant force acts, is called the center of
buoyancy
(d) Center of buoyancy is located above the center of gravity of the displaced
liquid v
(e) Relative density of liquids can be determined by means of the depth of
flotation of hydrometer.
Ans: d

159.
According to the principle of buoyancy a body totally or partially immersed in
a fluid will be lifted up by a force equal to
(a) the weight of the body
(b) more than the weight of the body
(c) less than the weight of the body
(d) weight of the fluid displaced by the body
(e) weight of body plus the weight of the fluid displaced hy the body.
Ans: d

160. When
a body floating in a liquid, is displaced slightly, it oscillates about
(a) e.g. of body
(b) center of pressure
(c) center of buoyancy
(d) metacentre
(e) liquid surface.
Ans: d

161.
Buoyant force is
(a) resultant force acting on a floating body
(b) equal to the volume of liquid displaced
(c) force necessary to keep a body in equilibrium
(d) the resultant force on a body due to the fluid surrounding it
(e) none of the above.
Ans: d

l62. Ratio
of inertia force to surface Jension is known as
(a) Mach number
(b) Froude number
(c) Reynold’s number
(d) Weber’s number
(e) none of the above.
Ans: d

163. A
ship whose hull length is 100 m is to travel at 10 m/sec. For dynamic
similarity,
at what velocity should a 1:25 model be towed through water ?
(a) 10 m/sec
(b) 25 m/sec
(c) 2 m/sec
(d) 50 m/sec
(e) 250 m/sec.
Ans: c

164. A
model of a reservior is drained in 4 mts by opening the sluice gate. The model
scale is 1: 225. How long should it take to empty the prototype ?
(a) 900 minutes
(b) 4 minutes
(c) 4 x (225)3/2 minutes
(d) 4 (225)1/3 minutes
(e) 4 x V225 minutes.
Ans: e

165. A model
of torpedo is tested in a towing tank at a velocity of 25 m/sec. The prototype
is expected to attain a velocity
of 5 m/sec. What model scale has been used ?
(a) 1 : 5
(b) 1 : 2.5
(c) 1 :25
(d) 1:V5″
(e) 1 : 53/2
Ans: a

166. Ratio
of inertia force to elastic force is known as
(a) Mach number
(b) Froude number
(c) Reynold’s number
(d) Weber’s number
(e) none of the above.
Ans: a

167. For a
floating body to be in stable equilibrium, its metacentre should be
(a) below the center of gravity
(b) below the center of buoyancy
(c) above the center of buoyancy
(d) between e.g. and center of pressure
(e) above the center of gravity.
Ans: e

16 For a
floating body to be in equilibrium
(a) meta center should be above e.g.
(b) center of buoyancy and e.g. must lie on same vertical plane
(c) a righting couple should be formed
(d) all of the above
(e) none of the above.
Ans: d

169. The
two important forces for a floating body are
(a) buoyancy, gravity
(b) buoyancy, pressure
(c) buoyancy, inertial
(d) inertial, gravity
(e) gravity, pressure.
Ans: a

170.
Choose the wrong statement
(a) The center of buoyancy is located at the center of gravity of the displaced
liquid
(b) For stability of a submerged body, the center of gravity of body must lie
directly below the center of buoyancy
(c) If e.g. and center of buoyancy coincide, the submerged body must lie at
neutral equilibrium for all positions
(d) For stability of floating cylinders or spheres, the e.g. of body must lie
below the center of buoyancy
(e) All floating bodies are stable.
Ans: e

171.
Center of pressure on an inclined plane is
(a) at the centroid
(b) above the centroid
(c) below the centroid
(d) at metacentre
(e) at center of pressure.
Ans: c

172. An
open vessel of water is accelerated up an inclined plane. The free water
surface will
(a) be horizontal
(b) make an angle in direction of inclination of inclined plane
(c) make an angle in opposite direction to inclination of inclined plane
(d) any one of above is possible
(e) none of the above.
Ans: c

173. The
line of action of the buoyant force acts through the centroid of the
(a) submerged body
(b) volume of the floating body
(c) volume of the fluid vertically above the body
(d) displaced volume of the fluid
(e) none of the above.
Ans: d

174.
Resultant pressure of the liquid in the case of an immersed body acts through
(a) center of gravity
(b) center of pressure
(c) metacentre
(d) center of buoyancy
(e) in between e.g. and center of pressure.
Ans: b

175. The
center of gravity of the volume of the liquid displaced by an immersed body is
called
(a) center of gravity
(b) center of pressure
(c) metacentre
(d) center of buoyancy
(e) centroid.
Ans: d

176.
Differential monometer is used to measure
(a) pressure in pipes, channels etc.
(b) atmospheric pressure
(c) very low pressure
(d) difference of pressure between two points
(e) velocity in pipes
Ans: d

177. The
pressure in the air space above an oil (sp. gr. 0.8) surface in a tank is 0.1
kg/cm”.
The pressure at 2.5 m below the oil surface will be
(a) 2 meters of water column
(b) 3 meters of water column
(c) 3.5 meters of water column
(d) 4 m of water column
(e) none of the above.
Ans: b

17 The
time oscillation of a floating body with increase in metacentric height will be
(a) same
(b) higher
(c) lower
(d) lower/higher depending on weight of body
(e) unpredictable.
Ans: c

179. In an
immersed body, center of pressure is
(a) at the center of gravity
(b) above the center of gravity
(c) below be center of gravity
(d) could be above or below e.g. depending on density of body and liquid
(e) unpredictable.
Ans: c

180. The
normal stress is same in all directions at a point in a fluid
(a) only when the fluid is frictionless
(b) only when the fluid is incompressible and has zero viscosity
(c) when there is no motion of one fluid layer relative to an adjacent layer
(d) irrespective of the motion of one fluid layer relative to an adjacent layer
(e) in case of an ideal fluid.
Ans: c

181.
Select the correct statement
(a) Local atmospheric pressure depends upon elevation of locality only
(b) Standard atmospheric pressure is the mean local atmospheric pressure a* sea
level
(c) Local atmospheric pressure is always below standard atmospheric pressure
(d) A barometer reads the difference be-tween local and standard atmospheric
pressure
(e) Gauge piessure is equal to atmospheric pressure plus instrument reading.
Ans: b

184. For
measuring flow by a venturimeter, if should be installed in
(a) vertical line
(b) horizontal line
(c) inclined line with flow downward
(d) inclined line with upward flow
(e) in any direction and in any location.
Ans: e

185. Total
pressure on a lmxlm gate immersed vertically at a depth of 2 m below the free
water surface will be
(a) 1000 kg
(b) 4000 kg
(c) 2000 kg
(d) 8000 kg
(e) 16000 kg.
Ans: a

186. Hot
wire anemometer is used to measure
(a) pressure in gases
(b) liquid discharge
(c) pressure in liquids
(d) gas velocities
(e) temperature.
Ans: d

187.
Rotameter is a device used to measure
(a) absolute pressure
(b) velocity of fluid
(c) flow
(d) rotation
(e) velocity of air.
Ans: c

18 Flow of
water in a pipe about 3 meters in diameter can be measured by
(a) orifice plate
(b) venturi
(c) rotameter
(d) pitot tube
(e) nozzle
Ans: d

189. True
one-dimensional flow occurs when
(a) the direction and magnitude of the veiocity at all points are identical
(b) the velocity of successive fluid par-ticles, at any point, is the same at
suc-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 plane
(e) velocity, depth, pressure etc. change from point to point in the fluid
flow.
Ans: a

190. An
ideal flow of any fluid must satisfy
(a) Pascal law
(b) Newton’s law of viscosity
(c) boundary layer theory
(d) continuity equation
(e) Bernoulli’s theorem.
Ans: d

191. In
the case of steady flow of a fluid, the acceleration of any fluid particle is
(a) constant
(b) variable
(c) zero
(d) zero under limiting conditions
(e) never zero.
Ans: c

193. Non
uniform flow occurs when
(a) the direction and magnitude of the velocity at all points are identical
(b) the velocity of successive fluid par-ticles, at any point, is the same at
suc-cessive periods of time
(c) the magnitude aricf 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 plane
(e) velocity, depth, pressure, etc. change from point to point in the fluid
flow.
Ans: e

194.
During the opening of a valve in a pipe line, the flow is
(c) uniform
(d) laminar
(e) free vortex type.
Ans: b

195.
Uniform flow occurs when
(b) the flow is streamline
(c) size and shape of the cross section in a particular length remain constant
(d) size and cross section change uniform¬ly along length
(e) flow occurs at constant fate.
Ans: c

196.
(e) true one-dimensional.
Ans: d

197.
(a) the direction and magnitude of the velocity at all points are identical
(b) the velocity of successive fluid par-ticles, at any point, is the same at
suc-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 plane
(e) velocity, depth, pressure, etc. change from point to point in the fluid
flow.
Ans: b

198 The
flow which neglects changes in a transverse direction is known as
(a) one dimensional flow
(b) uniform flow
(d) turbulent flow
(e) streamline flow.
Ans: a

199. The
flow in which each liquid particle has a definite path and their paths do not
cross each other is called
(a) one dimensional flow
(b) uniform flow