Fluid mechanics is a fundamental branch of physics and engineering that studies the behavior of fluids—liquids and gases—and the forces acting upon them. It encompasses two main areas: fluid statics, which examines fluids at rest and the pressure they exert, and fluid dynamics, which analyzes fluids in motion, including flow patterns, velocity, and energy.
Key principles include:
Pascal’s Law: Pressure applied to a confined fluid is transmitted equally in all directions, forming the basis for hydraulic systems.
Bernoulli’s Principle: In a steady flow, an increase in fluid velocity occurs with a decrease in pressure, explaining phenomena like lift in aircraft wings.
Viscosity: A measure of a fluid’s resistance to flow, which varies from low in gases to high in thick liquids like honey.
Reynolds Number: A dimensionless value that predicts whether fluid flow will be laminar (smooth) or turbulent (chaotic), based on factors like velocity and pipe diameter.
Fluid mechanics applies to diverse fields, including:
Aerodynamics: Designing aircraft and vehicles to minimize drag and optimize lift.
Hydrodynamics: Understanding water flow in rivers, oceans, and engineering systems like pumps and turbines.
Hydraulics: Power transmission in machinery, such as car brakes and construction equipment.
Environmental Science: Modeling weather patterns, ocean currents, and pollution dispersion.
Advancements in computational fluid dynamics (CFD) have enabled simulations for complex problems, from blood flow in medical devices to climate modeling. This discipline bridges theoretical physics with practical applications, driving innovation in energy, transportation, and beyond.
Table of contents
- Part 1: OnlineExamMaker – Generate and share fluid mechanics quiz with AI automatically
- Part 2: 20 fluid mechanics quiz questions & answers
- Part 3: OnlineExamMaker AI Question Generator: Generate questions for any topic
Part 1: OnlineExamMaker – Generate and share fluid mechanics quiz with AI automatically
OnlineExamMaker is a powerful AI-powered assessment platform to create auto-grading fluid mechanics assessments. It’s designed for educators, trainers, businesses, and anyone looking to generate engaging quizzes without spending hours crafting questions manually. The AI Question Generator feature allows you to input a topic or specific details, and it generates a variety of question types automatically.
Top features for assessment organizers:
● Prevent cheating by randomizing questions or changing the order of questions, so learners don’t get the same set of questions each time.
● AI Exam Grader for efficiently grading quizzes and assignments, offering inline comments, automatic scoring, and “fudge points” for manual adjustments.
● Embed quizzes on websites, blogs, or share via email, social media (Facebook, Twitter), or direct links.
● Handles large-scale testing (thousands of exams/semester) without internet dependency, backed by cloud infrastructure.
Automatically generate questions using AI
Part 2: 20 fluid mechanics quiz questions & answers
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1. Question: What is the SI unit of pressure?
A) Newton per meter squared
B) Pascal
C) Joule
D) Watt
Answer: B
Explanation: Pressure is defined as force per unit area, and the SI unit is the Pascal, which is equivalent to one Newton per square meter.
2. Question: According to Pascal’s law, pressure applied to a confined fluid is transmitted:
A) Only upwards
B) Undiminished in all directions
C) Only downwards
D) Only sideways
Answer: B
Explanation: Pascal’s law states that pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid.
3. Question: What does Bernoulli’s equation describe?
A) Conservation of mass in fluids
B) Conservation of energy in flowing fluids
C) Viscosity of fluids
D) Surface tension effects
Answer: B
Explanation: Bernoulli’s equation is derived from the conservation of energy principle and relates pressure, velocity, and elevation in a flowing fluid.
4. Question: In fluid statics, the pressure at a depth h in a fluid of density ρ is given by:
A) P = ρgh
B) P = mgh
C) P = F/A
D) P = v^2/2
Answer: A
Explanation: The hydrostatic pressure formula is P = ρgh, where ρ is the fluid density, g is gravity, and h is the depth.
5. Question: What is the continuity equation for an incompressible fluid?
A) A1V1 = A2V2
B) P1 + ρgh1 = P2 + ρgh2
C) F = ma
D) ρ1V1 = ρ2V2
Answer: A
Explanation: For an incompressible fluid, the continuity equation states that the product of cross-sectional area and velocity is constant, so A1V1 = A2V2.
6. Question: Reynolds number is a dimensionless quantity that predicts:
A) Fluid density
B) Type of flow (laminar or turbulent)
C) Pressure drop in pipes
D) Buoyant force
Answer: B
Explanation: Reynolds number (Re = ρVD/μ) determines whether the flow is laminar (Re < 2000) or turbulent (Re > 4000), based on fluid properties and flow conditions.
7. Question: Archimedes’ principle states that the buoyant force on an object is equal to:
A) The weight of the object
B) The weight of the fluid displaced by the object
C) The volume of the object
D) The density of the fluid
Answer: B
Explanation: The buoyant force equals the weight of the fluid displaced, which explains why objects float or sink based on their density relative to the fluid.
8. Question: In laminar flow, the fluid particles:
A) Move in straight lines parallel to the flow direction
B) Mix chaotically
C) Form eddies and vortices
D) Have high Reynolds numbers
Answer: A
Explanation: Laminar flow is characterized by smooth, orderly motion where fluid layers slide past one another in parallel paths.
9. Question: What is viscosity?
A) The resistance to flow of a fluid
B) The density of the fluid
C) The speed of the fluid
D) The pressure in the fluid
Answer: A
Explanation: Viscosity measures a fluid’s internal resistance to flow, with higher viscosity fluids like honey flowing more slowly than low-viscosity fluids like water.
10. Question: For an ideal fluid, which of the following is true?
A) It has viscosity
B) It is incompressible and has no viscosity
C) It is compressible
D) It experiences turbulence
Answer: B
Explanation: An ideal fluid is a theoretical concept that is incompressible and has zero viscosity, simplifying fluid dynamics equations.
11. Question: The drag force on an object moving through a fluid depends on:
A) The shape and speed of the object only
B) The density of the fluid, speed, and object’s size
C) Gravity alone
D) Temperature of the fluid
Answer: B
Explanation: Drag force is given by formulas like the drag equation, which includes fluid density, object velocity, size, and shape.
12. Question: In a Venturi meter, the pressure is lowest at:
A) The entrance
B) The throat
C) The exit
D) Midway between entrance and throat
Answer: B
Explanation: According to Bernoulli’s principle, velocity increases and pressure decreases at the narrower throat of the Venturi meter.
13. Question: Surface tension is caused by:
A) Adhesive forces between fluid and container
B) Cohesive forces between fluid molecules
C) Gravitational forces
D) Pressure differences
Answer: B
Explanation: Surface tension arises from the cohesive forces between molecules at the surface of a liquid, creating a “skin” effect.
14. Question: What is the condition for a fluid to be in streamline flow?
A) High viscosity
B) Low Reynolds number
C) High pressure
D) Turbulent motion
Answer: B
Explanation: Streamline (or laminar) flow occurs when the Reynolds number is low, indicating smooth flow without mixing.
15. Question: The equation for dynamic viscosity is related to:
A) Shear stress and velocity gradient
B) Pressure and volume
C) Density and gravity
D) Flow rate and area
Answer: A
Explanation: Dynamic viscosity (μ) is defined as the ratio of shear stress to the velocity gradient in the fluid.
16. Question: In fluid dynamics, the lift force on an airfoil is primarily due to:
A) Bernoulli’s principle
B) Gravitational pull
C) Friction with air
D) Surface tension
Answer: A
Explanation: Lift is generated by the pressure difference created by varying air speeds over and under the airfoil, as per Bernoulli’s equation.
17. Question: For two pipes in parallel, the total flow rate is:
A) The sum of the flow rates in each pipe
B) The difference of the flow rates
C) Equal to the flow rate in the larger pipe
D) Zero
Answer: A
Explanation: In parallel pipes, the total flow rate is the algebraic sum of the individual flow rates, as the flows combine.
18. Question: What happens to the pressure in a fluid when it flows from a wide pipe to a narrow pipe?
A) Increases
B) Decreases
C) Remains the same
D) Depends on temperature
Answer: B
Explanation: By the continuity equation and Bernoulli’s principle, velocity increases in a narrow pipe, causing pressure to decrease.
19. Question: The capillary rise in a tube is inversely proportional to:
A) The radius of the tube
B) The density of the liquid
C) Surface tension
D) Contact angle
Answer: A
Explanation: Capillary rise height is given by h = (2σ cosθ)/(ρgr), so it is inversely proportional to the radius r of the tube.
20. Question: In a centrifugal pump, the fluid is accelerated by:
A) Impeller blades
B) Pistons
C) Gravity
D) Pressure gradients
Answer: A
Explanation: A centrifugal pump uses rotating impeller blades to increase the kinetic energy of the fluid, converting it to pressure energy.
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