## Fluid Mechanics Multiple Choice QuestionsOur top 50 Fluid Mechanics questions and answers focus on all the areas of this subject. It covers over more than 50 topics in Fluid Mechanics. Anyone who wishes to sharpen their knowledge, preparing for the interviews, or preparing for the entrance exam can practice these Fluid Mechanics Questions. 1) A rectangular tank is moving horizontally in the direction of its length with a constant acceleration of 4.8 m/s2. The size of the tank is 7 m, and the depth is 1.5 m. If the tank is open at the top, then calculate the maximum pressure intensity at the bottom. - 3.15 N/cm2
- 6.3 N/cm2
- 1.6 N/cm2
- 12.6 N/cm2
tanθ=a/g tanθ=4.8/9.8 θ=26.07⁰ h= d+(L/2)tanθ = 1.5+3.5tan26.07 = 3.21 m p=ρ*g*h =3.15 N/cm2. 2) A rectangular tank is moving horizontally in the direction of its length with a constant acceleration of 4.5 m/s2.The tank's size, width, and depth are 7 m, 3m, 2.5m, respectively. If the tank is open at the top, then calculate the total force due to water acting on the tank's higher pressure end. - 2.14 MN
- 1.07 MN
- 1.07 MN
- 4.28 MN
tanθ=a/g tanθ=4.5/9.8 θ=24.64⁰ h= d+(L/2)tanθ = 2.5+3.5tan24.64 = 4.1 m F=wAĥ =9810*2.68*4.1 = 1.07 MN. 3) A tank containing water upto a depth of 650 mm is stationary. Find the force exerted by the fluid of specific gravity .55 on the side of the tank. The width of the tank is 1.5m - 3419.4N
- 1709.9 N
- 1367.75 N
- 6838.8 N
p=ρ*g*h =550*9.81*0.65 =3507 N/m2 F=wAĥ = 0.5*0.65*3507*1.5 = 1709.7N. 4) If the tank is moving vertically, which of its component is subjected to maximum total pressure? - The higher part of vertical walls
- The lower part of vertical walls
- Base
- None of the above
5) In a stationary fluid, how does the local pressure of the liquid vary? - In the horizontal direction, only
- With depth only
- Neither with depth nor along the horizontal direction
- Both with depth and along the horizontal direction
6) Which of the following cannot be the value of a fluid's absolute pressure at any point? - 1.013 bar
- 0
- 200 bar
- - 1 bar
7) In a U-tube manometer, one end is open to the atmosphere, the other end attached to a pressurized gas of gauge pressure 40 kPa. The height of the fluid column on the atmospheric side is 60 cm, and that on the gas side is 30 cm. The manometric fluid used is: (Take g = 9.8 m/s - Liquid ammonia
- Water
- Mercury
- Oil
8) Find the center of buoyancy's position for a wooden block of width 3.5 m and depth 1 m when it floats horizontally in the water. The density of the wooden block is 850 kg/m3, and its length 7.0 m. - 0.85
- 0.95
- 1.65
- 1.05
Volume of water displaced = Weight of water displaced/weight density of water = 20.825 m3. h=20.825/3.5*7=0.85 m. 9) A body of dimensions 2.7 m * 3.8 m * 2.5 m, weighs 2500 N in water.Find its weight in air. - 508.25 kN
- 254.12 kN
- 127.06 kN
- 101.65 kN
10) What happens to the buoyant force acting on the airship as it rises in the air? - Buoyant force decreases
- Buoyant force increases
- Buoyant force first increases then show a decrease
- Buoyant force remains constant
11) A uniform body of size 4 m long * 2.5 m wide * 1.5 m deep floats in water. What is the weight of the body if the depth of immersion is 1 m? - 294.3 kN
- 147.1 kN
- 588.6 kN
- 73.5 kN
12) A block of material of specific gravity 0.45 floats in water. Determine the block's meta-centric height if its size is 3 m * 2 m* 0.8 m. - 0.376 m
- 0.506 m
- 0.127 m
- 1.012 m
Metacentric height = I/∀ - BG I = bd³/12 = 3*2³/12 ∀ = 3*2*0.8 Metacentric height = 0.376 m. 13) A solid cylinder of diameter 5.0 m has a height of 6.0 m. Find the cylinder's meta-centric height if the specific gravity of the material of the cylinder 0.45 and it is floating in water with its axis vertical. State whether the equilibrium is stable or unstable. - -0.61 m
- -0.29 m
- 0.14 m
- -1.16 m
Metacentric height=I/∀ -BG I=π*r ∀=π*r*r*h=π*2.5*2.5*6 Metacentric height=-0.61. 14) A solid cylinder of 15 cm diameter and 40 cm long consists of two parts made of different materials. The first part at the base is 1.5 cm long and of specific gravity=6.5. The other part of the cylinder is made of the material having a specific gravity of 0.75. State if it can float vertically in the water. - Data insufficient
- It will float
- It will not float
- None of the mentioned
By principle of buoyancy, Weight of cylinder = Weight of water displaced h=38.625 AB=19.31 BG=14.25-19.31= -4.79 GM= Metacentric height=I/∀ -BG = 6.16 As metacentric height is positive, it will float. 15) Which method is used exclusively in fluid mechanics? - Eulerian method
- Lagrangian method
- Neither Lagrangian nor Eulerian method
- Both Lagrangian and Eulerian methods
16) What type of flow can be taken for granted in a pipe of a uniform cross-section? - Unsteady
- Steady
- Non-Uniform
- Uniform
17) "The velocity of entrance and exit through a nozzle remains the same." Is this even possible? - only if the flow is laminar
- only if the flow is compressible
- never possible
- only if the flow is rotational
18) What will be the shape of the pathline for a one-dimensional flow be like? - Parabolic
- Straight line
- Elliptical
- Hyperbolic
19) What is the maximum number of times the two particles' pathlines can intersect in a one-dimensional flow? - 1
- 0
- Infinite
- 2
20) The streamlines of the particles in a flow are recorded. If the streamline distribution remains the same even after some time, what type of flow can it be? - Unsteady
- Steady
- non-uniform
- uniform
21) The path taken by the smoke coming out of a chimney (in concentric circles) represents a - Streamline
- Pathline
- Streamtube
- Streakline
22) If a liquid enters a pipe of diameter d with a velocity v, what will its velocity at the exit if the diameter reduces to 0.5d? - 0.5v
- V
- 4v
- 2v
23) Which method is most commonly used in fluid mechanics for analysis? - Eulerian Method
- Lagrangian method
- Control volume analysis
- None of the mentioned
24) For incompressible fluid flow, if area reduces, then what is the effect on the velocity. - Decreases
- Increases
- first decreases, then increase
- first increases, then decrease
Area × velocity = constant Hence, as the area decreases, velocity increases. 25) For compressible fluid flow in a pipe, having a decrease in specific gravity, what will be the effect of a reduction in diameter? - It will cause a decrease in velocity
- It will cause an increase in velocity
- It remains constant
- None of the mentioned
ρ*A*v = constant Hence, as density and area decrease, velocity is bound to increase. 26) The diameter of a pipe in section 1 is 9 cm. If the velocity of water flowing through the line at section 1 is 4.8 m/s, and section 2 is nine m/s, Determine the area at section 2. - 67.86 m2
- 33.93 m2
- 38.66 m2
- 16.96 m2
According to continuity equation, Area × velocity = constant Area1*Velocity1 = Area2*Velocity2 (Area1*Velocity1)/Velocity2=Area2 Area 2= 33.93 m2. 27) Which equation must be perfunctorily satisfied while dealing with fluid flow problems? - Newton's third law
- Newton's second law
- Continuity equation
- Law of conservation of momentum
28) When a fluid element moves from one position to another, what type of motion is it? - Linear Deformation
- Linear Translation
- Rotation
- Angular Deformation
29) If there is a change in angle contained by two sides. the average of the curve is - Linear Deformation
- Linear Translation
- Rotation
- Angular Deformation
30) What is the magnitude of vorticity? - Thrice of angular rotation
- Twice of angular rotation
- Same as angular rotation
- Two and half times of angular rotation
31) The flow of fluid along a curvilinear or curved path is known as - Vortex Flow
- Sink Flow
- Circular Flow
- Curvilinear Flow
32) Which of the following is not an example of forced vortex flow? - The flow of liquid inside the impeller of a centrifugal pump
- The liquid contained in the cylinder rotated about its axis
- The flow of the fluid around a circular bend in a pipe
- The flow of water through the runner of a turbine
33) The characteristic of Ideal fluid is - Inviscid
- Incompressible
- Shear stress has a constant, non-zero value
- Fluid velocity is uniform
34) Which of the following is not a case of ideal fluid flow? - Uniform Flow
- Forced vortex Flow
- Superimposed flow
- Sink Flow
35) What is a special characteristic of uniform flow parallel to X-axis? - Acceleration is constant
- Velocity is constant
- X- component of velocity is constant
- None of the mentioned
36) What is the nature of streamlines of free vortex flow? - Non-concentric
- Concentric
- Linear
- None of the mentioned
37) When is air assumed to be incompressible? - Independent of its speed
- At low speed
- At high speed
- None of the mentioned
38) When a uniform flow is flowing through a doublet, the resultant flow obtained is - Flow past a circular cylinder
- Flow past a Rankine oval of equal axes
- Both
- None
39) How many stagnation points are present in a source and sink pair in a uniform flow - One
- Two
- Three
- None
40) What is the term used for a case where source and sink( both of them are of equal magnitude) approach each other such, distance between them reduces, and the product of distance and discharge magnitude remains constant. - A doublet source in uniform
- A plain pair
- Couette flow
- Hagen Poiseuille flow
41) What is the pressure in Pascals at a depth of 1m below the water surface? - 980 Pa
- 98100 Pa
- 1 Pa
- 98 Pa
42) The pressure at any given point of a non-moving fluid is called the _______ - Atmospheric Pressure
- Gauge Pressure
- Hydrostatic Pressure
- Differential Pressure
43) What type of liquids are measured using a manometer? - Medium Liquids
- Heavy Liquids
- Heavy and light liquid
- Light Liquid
44) Which among these devices are the best suited for the measurement of high-pressure liquids with high accuracy? - Ionization Gauge
- Vacuum Gauge
- Manganin wire pressure
- Dead Weight Gauge
45) Which one of the following statements is true regarding pressure? - The pressure is a vector quantity
- The pressure is a scalar quantity
- The pressure is a vector quantity only when the area is infinitesimally small
- The pressure is a scalar quantity only when the area is infinitesimally small
46) A Hydraulic press has a ram of 30 cm diameter and a plunger of 2 cm diameter. It is used for lifting a weight of 35 kN. Find the force required at the plunger. - 311.1 kN
- 233.3 kN
- 155.5 kN
- 466.6 kN
F/a=W/A F=(35000*3.142*.02*.02)/(3.142*0.3*0.3) =155.5 kN. 47) The pressure at a point in the fluid is 4.9 N/cm2. Find height when the fluid under consideration is in oil of specific gravity of 0.85. - 8.74 m
- 17.49 m
- 11.66 m
- 5.83 m
Height=p/ρg =48620/850*9.81 =5.83 m. 48) If the fluid is at rest in a narrow mouth container at a certain column height and the same fluid is at rest at the same column height in a box having a broad mouth, will the pressure be different at a certain depth from fluid surface. - Pressure will be less for narrower mouth
- Pressure will be more for narrower mouth
- Pressure will be the same for both.
- None of the mentioned
49) Calculate the hydrostatic pressure for water moving with the constant velocity at a depth of 5 m from the surface. - 98 kN/m2
- 49 kN/m2
- since the fluid is in motion, we cannot analyze
- None of the mentioned
p= ρgh. 50) Which device is popularly used for measuring the difference of low pressure? - U-tube Differential Manometer
- Inverted U-tube Differential Manometer
- Vertical Single column manometer
- Inclined Single column manometer
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