Hydraulics And Fluid Mechanics In Me — Part 1 MCQs with Explanations

A flow in which the quantity of liquid flowing per second remains constant is referred to as steady flow . Steady Flow: In steady flow , the flow parameters such as velocity, pressure, and density do not change with time at any given point. This means that the amount of liquid flowing per second (the flow rate) remains constant over time. Streamline Flow: Streamline flow , also known as laminar flow, describes the smooth, orderly movement of fluid in which layers of fluid flow parallel to each other. While streamline flow can be steady, it is not specifically defined by the constancy of flow rate. Turbulent Flow: Turbulent flow is characterized by chaotic and irregular fluid motion, where the flow rate can fluctuate. It is not defined by a constant flow rate. Unsteady Flow: Unsteady flow occurs when the flow parameters change with time at any given point. This means that the flow rate is not constant, and the quantity of liquid flowing per second can vary. Therefore, the correct answer is Option A: Steady .

When a liquid flows through a pipe, the velocity distribution across the pipe's cross-section depends on the viscosity of the fluid and the nature of flow (whether laminar or turbulent). In laminar flow, which occurs at lower velocities and typically in small diameter pipes or at low Reynolds numbers, the velocity profile is parabolic. Let's analyze each option: Option A: "Maximum at the centre and minimum near the walls" - This is incorrect for laminar flow. In laminar flow, the velocity is highest at the centre of the pipe and decreases linearly to zero at the walls. Option B: "Minimum at the centre and maximum near the walls" - This is incorrect. In laminar flow, the velocity is zero at the walls and increases parabolically to a maximum at the centre. Option C: "Zero at the centre and maximum near the walls" - This is incorrect. In laminar flow, the velocity is maximum at the centre and decreases smoothly to zero at the walls. Option D: "Maximum at the centre and zero near the walls" - This is correct for laminar flow. The velocity profile is parabolic, with the maximum velocity occurring at the centre of the pipe and decreasing to zero at the walls. Therefore, the correct answer is Option D: Maximum at the centre and zero near the walls .

The efficiency of a water turbine or vane is maximized when the vane velocity matches half of the jet velocity. This condition ensures that the maximum energy transfer occurs from the jet to the vane. Let's analyze each option: Option A: "One-half" - This is correct for achieving maximum efficiency. When the vane velocity is half of the jet velocity, it allows for optimal energy transfer from the jet to the vane. Option B: "One-third" - This is incorrect. A vane velocity of one-third of the jet velocity does not maximize efficiency; it would result in lower energy transfer. Option C: "Two-third" - This is incorrect. A vane velocity of two-thirds of the jet velocity is not optimal for maximum efficiency in energy transfer. Option D: "Three-fourth" - This is incorrect. A vane velocity of three-fourths of the jet velocity is also not optimal for maximum efficiency. Therefore, the correct answer is Option A: One-half .

The total pressure on the top of a closed cylindrical vessel completely filled with a liquid is directly proportional to (radius) 4 . This phenomenon is a result of the distribution of pressure in a fluid due to its weight. When a vessel is completely filled with liquid, the pressure at a specific depth is determined by the weight of the liquid above that level. The pressure at any point within a static fluid is proportional to the height of the fluid column above that point. For a cylindrical vessel, the pressure distribution is influenced by the cross-sectional area, which is proportional to the square of the radius. Since the pressure is directly related to the height of the liquid column and the area of the cross-section (which is proportional to the radius squared), the total pressure on the top of the vessel will be directly proportional to (radius) 2 * (radius) 2 , which simplifies to (radius) 4 .

In a pipe flowing under pressure, the velocity gradient represents the change in velocity across the cross-section of the pipe. When the velocity gradient is zero, it means that the velocity is constant at that point, and there is no change in velocity with respect to distance. This condition occurs at the centerline of the pipe, where the velocity is at its maximum and is constant. Shear stress is the force parallel to the surface that one layer of fluid exerts on an adjacent layer as they slide past each other. When the velocity gradient is zero, it implies that there is no change in velocity, and, consequently, there is no relative motion between fluid layers. As a result, the shear stress at the centerline of the pipe, where the velocity gradient is zero, will be Option C: Zero . There is no relative motion between fluid layers, so the shear stress is minimum or effectively non-existent at this location.

Manometers are devices used for measuring pressure, typically in fluids. The liquid used in manometers should have high density . This is because higher density liquids are less affected by small changes in pressure, providing more accurate measurements. Option A: Low density Low density liquids would be more sensitive to pressure changes, which could lead to less accurate readings. Option C: Low surface tension Surface tension is not a critical factor in the selection of the liquid for a manometer. It doesn't directly impact the accuracy of pressure measurements. Option D: High surface tension High surface tension liquids tend to form menisci in narrow tubes, which could affect the accuracy of pressure measurements in a manometer. Therefore, the correct answer is option B: High density .

Trapezoidal is the correct answer to “The Cipoletti weir is a __________ weir.”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

To lift small quantity of water to a greater height when a large quantity of water is available at a smaller height is the correct answer to “A hydraulic ram is a device used to”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Inversely proportional to its distance from the centre is the correct answer to “The tangential velocity of the water element having a free vortex is”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Metacentre is the correct answer to “When a body, floating in a liquid, is given a small angular displacement, it starts oscillating about a point known as”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Geometric similarity is the correct answer to “If the ratios of all the corresponding linear dimensions are equal, then the model and the prototype are said to have”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

All of these is the correct answer to “The coefficient of viscosity may be determined by”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Zero is the correct answer to “The horizontal component of buoyant force is”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Discharge a diameter is the correct answer to “Puck up the wrong statement about centrifugal pump”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Three to four times is the correct answer to “The length of the divergent cone in a Venturimeter is __________ that of the convergent cone.”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

$$\frac{{2{\text{LAN}}}}{{60}}$$ is the correct answer to “The discharge of a double acting reciprocating pump is (where L = Length of stroke, A = Cross-sectional area of piston and N = Speed of crank in r.p.m.)”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Two-dimensional flow is the correct answer to “A flow whose streamline is represented by a curve, is called”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Weight of the liquid displaced is the correct answer to “The buoyancy depends upon the”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

All of the above is the correct answer to “The magnitude of water hammer depends upon the”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Five times is the correct answer to “The width of the bucket for a Pelton wheel is generally ________ the diameter of jet.”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

1.2 times is the correct answer to “The depth of the bucket for a Pelton wheel is generally _________ the diameter of jet.”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Vortex flow is the correct answer to “When a cylindrical vessel, containing some liquid, is rotated about its vertical axis, the liquid surface is depressed down at the axis of its rotation and rises up near the walls of the vessel on all sides. This type of flow is known as”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Inlet of draft rube is the correct answer to “Which place in hydraulic turbine is most susceptible for cavitations”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Air lift pump is the correct answer to “Which of the following pump is successfully used for lifting water from deep wells”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Little above the tail race is the correct answer to “Impulse turbine is generally fitted”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Be fully immersed with top surface at fluid surface is the correct answer to “A metal with specific gravity of 'a' floating in a fluid of same specific gravity 'a' will”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

$$\frac{{2{\text{A}}\left( {\sqrt {{{\text{H}}_1}} - \sqrt {{{\text{H}}_2}} } \right)}}{{{{\text{C}}_{\text{d}}} \times {\text{a}}\sqrt {2{\text{g}}} }}$$ is the correct answer to “A tank of uniform cross-sectional area (A) containing liquid upto height (H 1 ) has an orifice of cross-sectional area (a) at its bottom. The time required to bring the liquid level from H 1 to H 2 will be”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

25 m to 250 m is the correct answer to “A Francis turbine is used when the available head of water is”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Square of ratio of diameters is the correct answer to “Pressure intensifier increases the pressure in proportion to”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

N-s/m2 is the correct answer to “The unit of dynamic viscosity in S.I. units is”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Viscous force is the correct answer to “Reynold's number is the ratio of inertia force to”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Gravity force is the correct answer to “Froude's number is the ratio of inertia force to”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Six is the correct answer to “The maximum number of jets, generally, employed in an impulse turbine without jet interference are”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

To lift larger load by the application of a comparatively much smaller force is the correct answer to “A hydraulic press is a device used”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Free vortex is the correct answer to “The flow of water through the hole in the bottom of a wash basin is an example of”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Spiral vortex flow is the correct answer to “Motion of a liquid in a volute casing of a centrifugal pump is an example of”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Highly turbulent flow is the correct answer to “A large Reynold number is indication of”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Stable equilibrium is the correct answer to “If a body floating in a liquid returns back to its original position, when given a small angular displacement, the body is said to be in”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Gravitational force is less than the up-thrust of the liquid is the correct answer to “When a body is placed over a liquid, it will float if”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.

Viscosity is the correct answer to “The property by virtue of which a liquid opposes relative motion between its different layers is called”. This question is standard in competitive examination syllabi for Hydraulics And Fluid Mechanics In Me.