Civil Engineering - Fluid Mechanics
Exam Duration: 45 Mins Total Questions : 30
the units of rate of strain in a fluid at a point are
- (a)
m
- (b)
m/s
- (c)
rad/s
- (d)
None of these
What will be the density of sea water at a depth of 1km, if the density at the surface is 1025kg/m3 and average bulk modulus of sea water is 2.35 x 109N/m2 ?
- (a)
4.387 kg/m3
- (b)
1035 kg/m3
- (c)
1025 kg/m3
- (d)
1029.387 kg/m3
A cylinder of 1 m diameter and 2 m length stays in equilibrium as shown.The specific gravity of other material will be
- (a)
0.75
- (b)
0.797
- (c)
0.757
- (d)
1.0
A metallic body floats at the interface of mercury (specific gravity 13.6) and water such that 40% of its volume is submerged in mercury and 60% in water.The density of the metal will be
- (a)
4780kg/rn3
- (b)
6040kg/rn3
- (c)
3020 kg/rn3
- (d)
8560 kg/rn3
An open cylindrical container, 0.3 m in diameter, 0.6 m high, two-third filled with oil of specific gravity 0.8 is rotated about its vertical axis.What win be the speed of rotation when the point at the centre of base is just exposed along with % of oil left in the container?
- (a)
18.68 rad/s, 50%
- (b)
22.9 rad/s, 100%
- (c)
22.9 rad/s, 75%
- (d)
18.68 rad/s. 75%
A solid body sinks in a fluid when
- (a)
the specific gravity of its material is greater than unity
- (b)
the buoyant force does not pass through meta centre
- (c)
the weight of the fluid displaced is less than the weight of the body
- (d)
the meta centre lies below the centre of gravity
For a two-dimensional irrotational flow, the velocity potential is defined as Φ=loge(X2+Y2).which of the following is a possible stream function Ψ for this flow?
- (a)
\({1\over2}tan^{-1}\left(y\over x\right)\)
- (b)
\(tan^{-1}\left(y\over x\right)\)
- (c)
\(2tan^{-1}\left(y\over x\right)\)
- (d)
\(tan^{-1}\left(x\over y\right)\)
The velocity field for a flow is given by v = (5x + 6y + 7z) i + (6x + 5y + 9z) j + (3x + 2y + A.z) k and the density varies as p = Po exp (- 2t) in order that mass is conserved, the value of ⋋. should be
- (a)
-12
- (b)
-10
- (c)
-8
- (d)
cannot be defined
A pitot static tube have coefficient of velocity 0.98, measures velocity of water in a pipe.The stagnation pressure recorded is 3 m and static pressure 2 m. What is the actual velocity in pipe?
- (a)
4.429 m/s
- (b)
4.341 m/s
- (c)
4.431 m/s
- (d)
Zero
A body 0 travels through water at a constant speed of 10 m/s as indicated. Velocities at points Band C in line with the path 0 are observed to be 4 m/s and 2 m/so These velocities are produced by the action of the moving body. What is PB - Pc?
- (a)
10 kN/m2
- (b)
14 kN/m2
- (c)
6 kN/m2
- (d)
Zero
In a steady, incompressible, fluid flow with uniform velocity distribution the momentum flux in a given X-direction past a given section is expressed as Mx is equal to
- (a)
pQv
- (b)
pQvx
- (c)
\(Q^2\over A\)
- (d)
\(pv^2\over2\)
A two dimensional jet strikes a fixed two dimensional plane at 45° to the normal to the plane.This causes the jet to split into two streams whose discharges are in the ratio.
- (a)
1.0
- (b)
2.41
- (c)
5.83
- (d)
1.414
in a model experiment with a weir, if the dimensions of the model weir are reduced by a factor k, the flow rate through the model weir is the following fraction of the flow rate through the prototype.
- (a)
K5/2
- (b)
K2
- (c)
1
- (d)
K-2
In the model of a highway bridge constructed to a scale of 1:25.The force of water on the pier was measured as 5N.The force on the prototype pier will be
- (a)
75015 N
- (b)
76225 N
- (c)
78125 N
- (d)
79165 N
In a boundary layer at a certain location the boundary layer thickness \(\delta=0.5\)cm, the displacement thickness\(\delta^*=0.15cm\) and momentum thickness θ=0.0585cm.The shape factor H at this location is
- (a)
2.564
- (b)
0.39
- (c)
3.333
- (d)
8.547
At the point of separation
- (a)
velocity is negative
- (b)
shear stress is zero
- (c)
shear stress is maximum
- (d)
pressure gradient is zero
What is the energy loss through a length of pipe from which all the discharge is taken out uniformly along its length, with respect to the cases when all the discharge is delivered to the end?
- (a)
\({2\over3}\)
- (b)
\({1\over3}\)
- (c)
\({3\over2}\)
- (d)
\({1\over2}\)
In a horizontal pipe flow if Δp is the pressure difference in pressure between two section distance L apart in a pipe of diameter D then \(\tau_0=\)
- (a)
\({\Delta pD\over 4L}\)
- (b)
\({\Delta pL\over D}\)
- (c)
\({1\over 8}\Delta pLV^2\)
- (d)
\(\sqrt{\Delta p\over 8}\)
The x-component of velocity in a 2-D incompressible flow is given by u = 1.5x. At the point(x, y) = (1,0), the y-component of velocity u = O.The equation for the y-component of the velocity is
- (a)
v = 0
- (b)
v = 1.5y
- (c)
v = -1.5y
- (d)
v = - 1.5x
The velocity field for a flow is given by v = (5x + 6y + 7z) i + (6x + 5y + 9z) j + (3x + 2y + ⋋z) k and density varies as P = Po exp (- 2 t). In order that the mass is conserved, the value of ⋋ shoule be
- (a)
-12
- (b)
-10
- (c)
-8
- (d)
10
The stream function is given by ψ = 2x2y + (x + 1)y2 the flow rate across a line joining points A (3, 0) and B (0, 2) is
- (a)
0.4units
- (b)
1.1units
- (c)
4units
- (d)
5units
The stream function for 2-D flow is given by ψ=2xy.The velocity at (2,2) is
- (a)
\(4\sqrt{2}\)
- (b)
4
- (c)
\(2\sqrt{2}\)
- (d)
\(\sqrt{2}\)
A homogeneous circular cylinder of length h, radius r and specific gravity s, floats in water. It is noted that \(r={2h\over 3}.\)Under which of the following conditions will the floatation will be unstable?
- (a)
0.11 ≤ s ≤ 0.22
- (b)
0.22 ≤ s ≤ 0.33
- (c)
0.33 ≤ s ≤ 0.66
- (d)
0.66 ≤ s ≤ 0.99
A compound pipe system consists of pipes of length 1800 m and diameter 50 cm, length 1200 m and diameter 40 cm, and length 600 m and diameter 30 cm connected in series. The equivalent length of 40 cm diameter pipe will be nearly.
- (a)
4300m
- (b)
440m
- (c)
4500m
- (d)
3600m
A metal cube of size 15 cm x 15 cm x 15 cm and specific gravity 8.6 is submerged in a two layered liquid, the bottom layer being mercury and the top layer being water. The percentage of the volume of the cube remaining above interface will be approximately
- (a)
68
- (b)
63
- (c)
40
- (d)
25
See the illustration given in figure and answer the following questions thereafter.
What is the intensity of pressure at point 1?
- (a)
pg(z2-z1)
- (b)
pg(z2-h)
- (c)
pgZ1
- (d)
pg(z1+h)
A 10 cm side cube weighing 5N is immersed in a liquid of relative density 0.8 contained in a rectangular tank of cross-sectional area 15cm x 15cm. If the tank contained liquid to a height of 8 cm before the immersion.
The buoyant force on the cube is
- (a)
10N
- (b)
5000N
- (c)
5N
- (d)
Cannot find
For pressure study in a flow meter in which an oil flows at an upstream velocity of 0.9 mls is to be estimated by model studies. A 1 : 6 scale model using water is used.The following data are relevant
Item | Prototype | Model |
---|---|---|
Density | 900 kg/m3 | 998 kg/m3 |
Viscosity | 0.104Pa-s | 1 x 10-3 Pa-s |
If the pressure drop in the model is 450 Pa, what will be the prototype pressure drop?
- (a)
250 kPa
- (b)
450kPa
- (c)
350kPa
- (d)
150kPa
An upward flow of oil (p = 800 kg /m3,μ= 0.8 kg /m - s) takes place under laminar conditions in a inclined pipe of 0.1 m diameter as shown in the figure. The pressure at sections 1 and 2 are measured as PI = 435 kN /m2 and P2 = 200 kN/m2
The discharge in the pipe is equal to
- (a)
0.100m3/s
- (b)
0.127m3/s
- (c)
0.144m3/s
- (d)
0.161m3/s
An automobile with projected area 2.6 m2 is running on a road with a speed of 120 km/h.The mass density and the kinematic viscosity of air are 1.2 kg/ m3 and 1.5 x 10-5 m2/s, respectively.The drag coefficient is 0.30.
The drag force on the automobile is
- (a)
620N
- (b)
600N
- (c)
580N
- (d)
520N