Fluid Mechanics Test 2

Question 1
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When a dolphin glides through air, it experiences an external pressure of 0.75 m of mercury. The absolute pressure on dolphin when it is 5 m below the free surface of the water is

A
0.10 N/mm²

B
0.5 N/mm²

C
1.0 N/mm²

D
0.15 N/mm²

Question 2
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Calculate the capillary rise or fall in a glass tube of 2.5 mm diameter when immersed vertically in mercury. Take surface tension σ = 0.52 N/m for mercury in constant with glass and angle of contact = 130°

A
0.8 cm, rise

B
0.4 cm rise

C
0.8 cm, fall

D
0.4 cm fall

Question 3
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Velocity profile over a curved surface is given as : \(\frac{u}{U} = 2{\left( {\frac{y}{\delta }} \right)^2} - {\left( {\frac{y}{\delta }} \right)^3}\)
The flow ______

A
has separated

B
will stick to surface

C
on verge of separation

D
None

Question 4
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The value of friction factor is misjudged by 25% in using Darcy-Weisbach equation. The resulting error in the discharge will be?

A
15.47%

B
-11%

C
-15.47%

D
11%

Question 5
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A centrifugal pump lifts 0.0125 m³ / s of water from a well with a static lift of 30 m. If the brake power of the driving electric motor is 5 kW, what is the overall efficiency of the pump-set?

A
57.6%

B
63.9%

C
65.3%

D
73.6%

Question 6
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Which of the following conditions is true regarding the validity of Pascal’s Law?
I- It is valid for ideal fluid in motion.
II- It is valid when real fluids with rigid body motion.

A
Only I true

B
Only II true

C
Both are false

D
Both are true

Question 7
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A head loss in 100 m length of a 0.1 m diameter pipe (f=0.02) carrying water is 10 m. The boundary shear stress in Pa is ____

A
2.4525

B
32.432

C
24.525

D
3.2432

Question 8
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Which of the following represents generalised continuity equation?

A
\(\frac{{\partial \rho }}{{\partial t}} + \frac{{\partial \left( {\rho u} \right)}}{{\partial x}} + \frac{{\partial \left( {\rho v} \right)}}{{\partial y}} + \frac{{\partial \left( {\rho w} \right)}}{{\partial z}} = 0\)

B
\(\frac{{\partial \rho }}{{\partial t}} + \;\nabla .\left( {\rho \vec V} \right) = 0\)

C
\(\frac{{D\rho }}{{Dt}} + \;\rho \left( {\nabla .\vec V} \right) = 0\)

D
None of these

Question 9
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In an orifice meter, coefficient of discharge is 0.58 and coefficient of vena contracta is 0.61, what is coefficient of velocity?

A
0.94-0.96

B
0.944-0.961

C
0.947-0.966

D
0.949-0.962

Question 10
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In a flow over a flat plate, laminar boundary layer exists where velocity distribution is
\(\frac{u}{U} = 0.5\frac{y}{\delta }\)
Ratio of momentum thickness to boundary layer thickness is____

A
1/2

B
1/4

C
1/6

D
1/8

Question 11
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Match the following:
P
Reynold’s model
i.
Cavitation
Q
Froude model
ii.
Capillary rise
R
Euler model
iii.
Pipe flow
S
Weber model
iv.
Flow over spillways

A
P – iii, Q – iv, R – ii, S - i

B
P – iii, Q – ii, R – iv, S - i

C
P – iv, Q – iii, R – I, S - ii

D
P – iii, Q – iv, R – I, S - ii

Question 12
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A 1 : 6 scale model of a passenger car is tested in a wind tunnel. The prototype velocity is 60 km/hr. The model drag is 250 N. The air in the model and prototype can be assumed to have the same properties. Which of the following statements are true?

A
The drag force on the prototype is 250 N

B
Power required to overcome the drag in the prototype is 4.167 kW

C
The drag force on the prototype is 0.25 N

D
The power required to overcome the drag in the prototype is 4.167 W

Question 13
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A smooth flat plate of total length 2 m is in parallel flow stream of water. The water has uniform free stream velocity of 1 m/s parallel to plate. The critical Reynolds number for a flat plate is 500000. Assume density of water is 1000 kg/m³ and dynamic viscosity of water 1 centipoises. What is the maximum distance measured (in m, up to two decimal places) from leading edge of plate, up-to which the boundary layer formed to be laminar?

A
0.4-0.6

B
0.44-0.61

C
0.47-0.66

D
0.49-0.62

Question 14
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In a small pipe of 0.5mm diameter and length 2m, water flows at 48cm³/minute. Viscosity is 1.92 centipoise at low temperature flow condition. Pressure drop in MPa is______

A
1.95-2.05

B
1.954-2.051

C
1.957-2.056

D
1.959-2.052

Question 15
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The velocity potential function in a two-dimensional flow field is given by Ø = x² – y². Which of the following statements are true?

A
Velocity at the point (1, 2) is 4.47 m/s

B
Velocity at the point (1, 2) is 20 m/s

C
Magnitude of discharge per unit width occurring between (1, 3) and (3, 4) is 18 units

D
Magnitude of discharge per unit width occurring between (1, 3) and (3, 4) is 81 units

Question 16
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For a two dimensional, unsteady flow of an incompressible fluid, the velocity field is given by V(2x² t + y) î - 4xyt ĵ Then which of the following statements are true?

A
Fluid flow is not possible.

B
Convective acceleration in x-direction at (1, 2) and t = 3 sec is + 72 m/s²

C
Local acceleration in y-direction at (1, 2) and t = 3 sec is 8 m/s²

D
Total acceleration at (1, 2) and t = 3 sec is 13.93 m/s²

Question 17
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A Fluid flow is given by
\(V = \left( {2x + \frac{{{y^3}}}{3} - {x^2}y} \right)\hat i + \left( {x{y^2} - \frac{{{x^3}}}{3} - 2y} \right)\hat j\)
Check whether the given flow is possible case of fluid flow or not. If possible, determine angular velocity about z-axis.

A
Possible; ω_z = y² + 2xy

B
Possible; ω_z = -5dy

C
Possible; ω_z = 0

D
Not possible

Submit Test

P	Reynold’s model	i.	Cavitation
Q	Froude model	ii.	Capillary rise
R	Euler model	iii.	Pipe flow
S	Weber model	iv.	Flow over spillways

Fluid Mechanics...

Question 1

0.10 N/mm2

0.5 N/mm2

1.0 N/mm2

0.15 N/mm2

Question 2

0.8 cm, rise

0.4 cm rise

0.8 cm, fall

0.4 cm fall

Question 3

has separated

will stick to surface

on verge of separation

None

Question 4

15.47%

-11%

-15.47%

11%

Question 5

57.6%

63.9%

65.3%

73.6%

Question 6

Only I true

Only II true

Both are false

Both are true

Question 7

2.4525

32.432

24.525

3.2432

Question 8

\(\frac{{\partial \rho }}{{\partial t}} + \frac{{\partial \left( {\rho u} \right)}}{{\partial x}} + \frac{{\partial \left( {\rho v} \right)}}{{\partial y}} + \frac{{\partial \left( {\rho w} \right)}}{{\partial z}} = 0\)

\(\frac{{\partial \rho }}{{\partial t}} + \;\nabla .\left( {\rho \vec V} \right) = 0\)

\(\frac{{D\rho }}{{Dt}} + \;\rho \left( {\nabla .\vec V} \right) = 0\)

None of these

Question 9

0.94-0.96

0.944-0.961

0.947-0.966

0.949-0.962

Question 10

1/2

1/4

1/6

1/8

Question 11

P – iii, Q – iv, R – ii, S - i

P – iii, Q – ii, R – iv, S - i

P – iv, Q – iii, R – I, S - ii

P – iii, Q – iv, R – I, S - ii

Question 12

The drag force on the prototype is 250 N

Power required to overcome the drag in the prototype is 4.167 kW

The drag force on the prototype is 0.25 N

The power required to overcome the drag in the prototype is 4.167 W

Question 13

0.4-0.6

0.44-0.61

0.47-0.66

0.49-0.62

Question 14

1.95-2.05

1.954-2.051

1.957-2.056

1.959-2.052

Question 15

Velocity at the point (1, 2) is 4.47 m/s

Velocity at the point (1, 2) is 20 m/s

Magnitude of discharge per unit width occurring between (1, 3) and (3, 4) is 18 units

Magnitude of discharge per unit width occurring between (1, 3) and (3, 4) is 81 units

Question 16

Fluid flow is not possible.

Convective acceleration in x-direction at (1, 2) and t = 3 sec is + 72 m/s2

Local acceleration in y-direction at (1, 2) and t = 3 sec is 8 m/s2

0.10 N/mm²

0.5 N/mm²

1.0 N/mm²

0.15 N/mm²

Convective acceleration in x-direction at (1, 2) and t = 3 sec is + 72 m/s²

Local acceleration in y-direction at (1, 2) and t = 3 sec is 8 m/s²

Total acceleration at (1, 2) and t = 3 sec is 13.93 m/s²

Possible; ω_z = y² + 2xy

Possible; ω_z = -5dy

Possible; ω_z = 0