Free Fluid Dynamics MCQs with Answers
363 Fluid Dynamics MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Fluid flow is described through speed, pressure and density, including steady flow and the equation of continuity for conserving mass. Bernoulli's equation relates pressure, speed and height, while fluid drag and terminal velocity explain why a falling object eventually moves at constant speed when drag balances its weight.
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Read the Fluid Dynamics notesFree MDCAT chapter notes with key terms363 questions · page 2 of 19
- A. Constant pressure
- B. Constant energy
- C. Constant mass flow rate
- D. Constant volume
Explanation: The same mass must pass every cross section each second, so where the area falls the speed must rise in proportion, which is the equation…
Correct answer: Constant mass flow rate- A. High velocity, high pressure
- B. High velocity, low pressure
- C. Low velocity, high pressure
- D. Low velocity, low pressure
Explanation: Continuity forces the speed up in the constriction, and since the total energy per unit volume is fixed, the gain in kinetic energy must…
Correct answer: High velocity, low pressure23. The curved shape of an airplane wing causes air to move faster over the top surface. This leads to:
- A. Greater pressure on the top
- B. Lower pressure on the top
- C. Equal pressure on both sides
- D. Zero pressure above the wing
Explanation: Faster flow means lower pressure by Bernoulli's principle, so the pressure above the wing falls below that underneath and the difference…
Correct answer: Lower pressure on the top- A. 9.8 m/s2 upward
- B. Zero
- C. 1 m/s2
- D. 9.8 m/s2 downward
Explanation: At terminal velocity the upward drag and upthrust exactly balance the weight, so the resultant force is zero and by Newton's second law…
Correct answer: Zero- A. Slightly less than critical velocity
- B. Equal to critical velocity
- C. Greater than critical velocity
- D. Increasing gradually but less than critical velocity
Explanation: Below the critical velocity the flow stays in orderly layers, and only once that threshold is passed does the motion break up into eddies…
Correct answer: Greater than critical velocity- A. Wing shape
- B. Aerofoil profile
- C. Curved profile
- D. None of these
Explanation: An aerofoil has a specially shaped cross-section that makes air move differently over its upper and lower surfaces, producing a pressure…
Correct answer: Aerofoil profile- A. Venturi meter
- B. Bernoulli equation
- C. Both A and B
- D. None
Explanation: A carburettor uses a narrow Venturi passage to increase air speed; Bernoulli's equation then explains the accompanying pressure decrease…
Correct answer: Both A and B- A. Bernoulli effect
- B. Torricelli effect
- C. Venturi effect
- D. Stokes effect
Explanation: The Venturi effect is the decrease in fluid pressure that occurs when fluid speed increases in a narrower section of a horizontal passage…
Correct answer: Venturi effect- A. Stationary
- B. Moving
- C. Moving slowly
- D. Moving fast
Explanation: Fast-moving air over the chimney opening has lower pressure according to Bernoulli's principle, creating a larger pressure difference that…
Correct answer: Moving fast- A. Mass
- B. Energy
- C. Momentum
- D. Fluid
Explanation: Bernoulli's equation follows from conservation of mechanical energy for steady, incompressible, non-viscous flow: pressure energy, kinetic…
Correct answer: Energy- A. Bernoulli's theorem
- B. Torricelli's theorem
- C. Venture relation
- D. All
Explanation: Torricelli's theorem gives the efflux speed from an opening as v = √(2gh), derived by applying Bernoulli's equation to the fluid surface…
Correct answer: Torricelli's theorem- A. Low
- B. High
- C. Constant
- D. Changes continuously
Explanation: For steady flow along a streamline, Bernoulli's equation shows that higher fluid speed corresponds to lower static pressure when the other…
Correct answer: Low- A. Mass
- B. Energy
- C. Momentum
- D. All
Explanation: The continuity equation comes from conservation of mass: the mass entering a pipe per second equals the mass leaving it per second.
Correct answer: Mass34. According to equation of continuity A1V1 = A2V2 = constant. The constant is equal to_______________?
- A. Flow rate
- B. Volume of fluid
- C. Mass of fluid
- D. The density of the fluid
Explanation: In A1V1 = A2V2, area in m² multiplied by speed in m/s gives m³/s, which is volume flow rate or discharge.
Correct answer: Flow rate- A. Rough
- B. Square
- C. Circular
- D. Spherical
Explanation: Stokes' law applies to a small spherical body moving slowly through a viscous fluid, where the drag force is F = 6π η r v.
Correct answer: Spherical- A. The shinning side of the ball
- B. Rough side
- C. The seam of the ball
- D. Goes straight
Explanation: In reverse swing, the ball moves towards its shiny side because the airflow and boundary-layer separation around an old, fast-moving ball…
Correct answer: The shinning side of the ball- A. Newtons law
- B. Pascals law
- C. Gauss law
- D. Stokes law
Explanation: For a small sphere moving slowly through a viscous fluid, Stokes' law gives drag force F = 6π η r v, where F is in N, η in Pa·s, r in m…
Correct answer: Stokes law- A. ML-1T-1
- B. M2L1T1
- C. ML1T-1
- D. M2L-1T-1
Explanation: The coefficient of viscosity is obtained from viscous force divided by velocity gradient and area: η = F/(A × velocity gradient), giving…
Correct answer: ML-1T-1- A. Kg.m.S-1
- B. Kg m-1.S-1
- C. Kg.m.S
- D. Kg-1.m-1.S-1
Explanation: From viscous force F = ηAv/l, η = Fl/(Av), giving units kg m s^-2 × m divided by m² × m s^-1 = kg m^-1 s^-1.
Correct answer: Kg m-1.S-1- A. Force
- B. Pressure
- C. Momentum
- D. Energy
Explanation: Pressure is force per unit area, so its dimensions are (MLT^-2)/L² = ML^-1T^-2.
Correct answer: Pressure