Fluid Mechanics Multiple Choice Questions (MCQ'S)
1. A cylindrical water tank has a 2 m height and 2 m diameter. The water is filled up in the tank. The total weight of the water is (in kg). if the density of water is 1000 kg/m3.
a. 6283.18
b. 3141.59
c. 1570.80
d. 2000
2. In the tank given in question 1, a small orifice is constructed to release the water. The orifice has a diameter of 2cm. Neglecting minor entry loss, the velocity of the flow (m/s) in the orifice is_______
a. 3.132
b. 6.264
c. 9.396
d. 12.528
3. As given in question 1 and question 2, the discharge in the orifice is ______ (in m3/s)
a. 0.19
b. 0.019
c. 0.0019
d. 1.9
4. The water tank mentioned in question1 is placed on 6m height building. A pipe is fitted with the orifice of the tank to the ground. What is velocity of the flow in the pipe at the ground level (m/s).
a. 3.132
b. 6.264
c. 9.396
d. 12.528
5. A river flows with a velocity of 3m/s. A boat of maximum velocity 5m/s needs to travel in the river upstream direction. The travel distance is 100km. the travel time of the boat is_______ (hours)
a. 833.33
b. 13.89
c. 3.472
d. None
6. The boat given in question-5 travels downstream in a distance of 100km. The travel time in hours is
a. 3.472
b. 3.968
c. 5.567
d. 9.259
7. The cross section of the river is approximated as given in the figure: Estimate the discharge (flow rate in m3/s) of the river flowing with a velocity 2m/s.
a. 5000
b. 22500
c. 2812.5
d. 5625
8. Reynolds number for a pipe of diameter ‘D’ is defined as
a. 𝝆VD/ μ
b. νD/𝝆
c. V2D/ g
d. ν3D/𝝆g
9. Atmospheric pressure is measured in terms of
a. Dyne/cm2
b. N/m2
c. bar
d. atm
e. all of the above
f. none of the above
10. As given in below figure what would be pressure at point A in kg/m2
a. 0
b. 7800
c. 5100
d. 2700
11. Newton’s law of viscosity relates
a. Pressure, velocity and viscosity
b. Shear stress and rate of angular deformation in a fluid
c. Shear stress, temperature, velocity and viscosity
d. None of the above
12. A control volume implies
a. An isolated system
b. A fixed region in space
c. A closed system
d. A specified mass in fluid flow
13. Match List 1 and List 2 and select the correct answer using the codes given below
List 1 List 2
P. Property which explains the spherical nature of a drop of a fluid 1. Viscosity
Q. Property which explains cavitation in fluid flow 2. Surface tension
R. Property which explains rise of water in trees 3. Compressibility
S. Property which explains flow of oil jet 4. Vapor pressure 5.Capillarity
a. P-3, Q-4, R-5, S-1
b. P-1, Q-2, R-3, S-4
c. P-2, Q-4, R-5, S-1
d. P-1; Q-2; R-4, S-5
14. The unit of kinematic viscosity of a fluid is
a. m2/s
b. N-s/m2
c. Pa-s/ m2
d. Kg-s2/ m2
15. With increase of temperature, viscosity of a gas
a. Does not change
b. Always increase
c. Always decrease
d. Cannot say
16. Which of the following statements are applicable for the concept of continuum fluid mechanics is
a. Assumes a continuous distribution of mass with in the matter or system with no empty space.
b. Properties of the system can be expressed as continuous functions of space and time
c. The mean free path of the molecule is much smaller compared to the characteristic dimension
d. All of the above
17. Shear stress in the Newtonian fluid is proportional to
a. Pressure
b. Strain
c. Strain rate
d. The inverse of viscosity
18. The phenomenon of surface tension arises due to intermolecular forces of
a. Only cohesion
b. Only adhesion
c. Both cohesion and adhesion
d. Cannot say
19. The locus of temporary locations of all the particles that have passed through a through a fixed point in the flow field is
a. Stream line
b. Streak line
c. Path line
d. None of the above
20. The flow in which velocity of a fluid at a particular fixed point change with time
a. Unsteady flow
b. Laminar flow
c. Steady flow
d. Smooth layered flow
21. A fluid is one which can be defined as a substance
a. Has same shear stress at all points
b. Can deform indefinitely under the action of the smallest shear force
c. Has the small shear stress in all directions
d. Is practically incompressible
22. Kinematic viscosity is defined as
a. Dynamic viscosity x density
b. Dynamic viscosity/density
c. Dynamic viscosity x pressure
d. Pressure x density
23. Poise is the unit of
a. Mass density
b. Kinematic viscosity
c. Viscosity
d. Velocity gradient
24. The lines A and B in the following graph represent :
a. Bingham plastic and Newtonian fluid
b. Pseudo plastic and Non-Newtonian dilatant
c. Pseudo plastic and Newtonian fluid
d. Cannot say
25. The velocity distribution for flow over a flat plate is given by u = 0.75y- y2 in which u is the velocity in m/s at a distance of y m above the plate. Determine the shear stress in N/m2 at y =0.15 m. Take dynamic viscosity of fluid as 8.5 poise.
26. The kinematic viscosity and specific gravity of a certain liquid are 5.58 x 10-4 m2/s and 2 respectively. Compute dynamic viscosity in Ns/m2.
Based on the below statement answer the question number 27 and 28
If 5 m3 of a certain liquid weighs 40 kN, calculate the mass density (kg/m3) and specific gravity of the liquid. Consider g as 9.81m/s2.
27. calculate the mass density (kg/m3) of the liquid
28. calculate the specific gravity of the liquid
29.for a fluid in motion, pressure at a point is same in all directions, then the fluid is
a. A real fluid
b. A Newtonian fluid
c. AnIdealfluid
d. A non-Newtonian fluid
30 .Shear stress develops on a fluid element, if the fluid
a. Is at rest
b. If the container is subjected to uniform linear acceleration
c. Is inviscid
d. Is viscous and the flow is non-uniform
31. A floating body with its center of gravity at G, center of buoyancy at B and metacenter at M is stable when
a. BM>BG
b. BM=BG
c. BM<BG
d. Cannot say
32.Select the correct statement
a. Absolute pressure = Gauge pressure – Atmospheric pressure
b. Gauge pressure= Absolute pressure – Atmospheric pressure
c. Absolute pressure = Atmospheric pressure + Vacuum pressure
d. Gauge pressure = Atmospheric pressure + Vacuum pressure
33. Atmospheric pressure held in terms of water column is
a. 7.5 m
b. 8.5 m
c. 9.81 m
d. 10.3 m
34. When a liquid is in contact with a solid, if the forces of adhesion between the molecules of the liquid and solid are greater than cohesive forces among liquid molecules, the phenomenon occurs is
a. Capillary depression
b. Capillary rise
c. No change in liquid surface
d. Cannot say
35. Center of pressure of a plane surface immersed in a liquid is
a. Above the center of gravity of the plane surface
b. At the center of gravity of the plane surface
c. Below the center of gravity of the plane surface
d. None of the above
36. The manometer suitable for measurement of small pressure difference in Liquids is
a. Inverted U-tube manometer
b. Ordinary U tube manometer
c.Inclinedmanometer
d. None of the above
37. For liquids, will capillarity height increase or decrease with the rise in temperature
a. Increase
b. Decrease
c. First decrease then increase
d. Remain constant
38. If a small concrete cube is submerged deep in still water in such a way that the pressure exerted on all faces of the cube is p, then the maximum shear stress developed inside the cube is
a.Zero
b. p/2
c. p
d. 2p
39. If the density of the flow-sediment suspension varies with depth from free surface h as ρ= 1024+h, calculate the pressure at the depth of 2 m (in kPa). Consider g = 9.81 m/s2
40. The pressure intensity at a point in a fluid is given by 3.924 N/cm2. Find the corresponding height of fluid (in m) when the fluid is in oil of specific gravity 0.9
41. The right limb of a simple U-tube manometer containing mercury is open to the atmosphere while the left limb is connected to a pipe in which fluid of specific gravity 0.9 is flowing. The sketch below shows the details of levels of fluid and mercury.
Find the pressure of a fluid in the pipe in N/cm2. Neglect atmospheric pressure.
Based on the below statement answer the question number 42 and 43
42. A circular plate of diameter 1.5 m which is placed vertically in such a way that the center of the plate is 3 m below the free surface of water.
43. Determine the total pressure (in N)
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