Here’s a set of 25 multiple-choice questions (MCQs) on Fluid Mechanics, tailored for civil engineering beginners. Each question has four options, an answer, and a brief explanation.

## 1. What is the study of fluid mechanics primarily concerned with?

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### Explanation:

Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasmas) and the forces on them, both at rest and in motion.

## 2. What is the principle behind Bernoulli's equation in fluid mechanics?

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### Explanation:

Bernoulli's equation in fluid mechanics is based on the conservation of energy, stating that the total energy in a flowing fluid remains constant along its path.

## 3. What does viscosity measure in a fluid?

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Viscosity is a measure of a fluid's resistance to deformation at a given rate, often described as its "thickness" or "internal friction".

## 4. What is laminar flow in fluid mechanics?

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Laminar flow is characterized by smooth or in parallel layers flow of fluid, with little or no mixing between the layers.

## 5. What is the purpose of a venturi meter in fluid mechanics?

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A venturi meter is a device used to measure the flow rate or velocity of a fluid through a pipeline.

## 6. What is hydrostatic pressure?

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Hydrostatic pressure is the pressure exerted by a fluid at rest, due to the force of gravity.

## 7. What does Reynolds number signify in fluid mechanics?

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Reynolds number is a dimensionless quantity used to predict flow patterns in different fluid flow situations, indicating whether the flow is laminar or turbulent.

## 8. What is the primary factor affecting the buoyancy of an object in a fluid?

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Buoyancy, the force exerted on an object that is partly or wholly immersed in a fluid, is primarily affected by the density of the fluid.

## 9. In fluid mechanics, what is a vortex?

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A vortex is a flow pattern in a fluid where the flow revolves around an axis line, which may be straight or curved.

## 10. What is the primary application of Pascal's law in civil engineering?

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### Explanation:

Pascal's law, which states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions, is fundamental in designing hydraulic systems such as lifts and pumps.

## 11. What is the primary cause of cavitation in fluid systems?

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### Explanation:

Cavitation occurs when there is a rapid change in fluid pressure, leading to the formation of vapor bubbles in areas where the pressure of the fluid falls below its vapor pressure.

## 12. What does the term 'specific gravity' refer to in fluid mechanics?

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### Explanation:

Specific gravity is a dimensionless quantity that describes the ratio of the density of a fluid to the density of a reference substance (usually water for liquids and air for gases).

## 13. What is the significance of the Darcy-Weisbach equation in fluid mechanics?

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The Darcy-Weisbach equation is used to calculate the head loss (or pressure loss) due to friction in a pipe or duct.

## 14. In fluid mechanics, what is the boundary layer?

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The boundary layer is a thin layer of fluid at the boundary of a solid body where the fluid velocity changes from zero at the surface (no-slip condition) to the free stream velocity.

## 15. What is meant by 'turbulent flow' in fluid mechanics?

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Turbulent flow is characterized by chaotic and irregular fluid motion, often occurring at high velocities and involving rapid variations in pressure and flow velocity.

## 16. How is the flow rate of a fluid typically measured?

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### Explanation:

The flow rate of a fluid is commonly measured using a flowmeter, a device that quantifies the amount of fluid passing through it.

## 17. What is the impact of fluid compressibility in fluid mechanics?

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Fluid compressibility, the measure of the change in volume of a fluid in response to a change in pressure, significantly influences how pressure is transmitted and fluid behaves in different systems.

## 18. What is a manometer used for in fluid mechanics?

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A manometer is an instrument used to measure the pressure of a fluid, or the difference in pressure between two points in a fluid.

## 19. What does the Archimedes' principle state about fluids?

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Archimedes' principle states that any object, wholly or partly immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

## 20. What is the primary application of the continuity equation in fluid mechanics?

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The continuity equation in fluid mechanics is a mathematical statement of the principle of mass conservation, stating that the mass flow rate in a fluid flow system remains constant.

## 21. What is capillarity in fluid mechanics?

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Capillarity, or capillary action, is the ability of a liquid to flow in narrow spaces without the assistance of external forces (like gravity), often against them, due to adhesive and cohesive forces of the liquid.

## 22. In fluid mechanics, what does the term 'streamline' represent?

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In fluid mechanics, a streamline is a line that is everywhere tangent to the velocity field of the fluid, representing the path that a fluid element will follow.

## 23. What is critical flow in fluid mechanics?

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Critical flow in fluid mechanics is a condition where the flow velocity of the fluid equals the speed of waves on the fluid's surface, often occurring at the threshold between subcritical and supercritical flow.

## 24. How is the Mach number relevant in fluid mechanics?

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### Explanation:

The Mach number in fluid mechanics is a dimensionless quantity that represents the ratio of the flow velocity past a boundary to the local speed of sound in the fluid.

## 25. What is the primary purpose of a pump in fluid mechanics?

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### Explanation:

In fluid mechanics, a pump is a device used to move fluids (including liquids and gases), typically by increasing the pressure, enabling their transportation from one location to another.