Two boats moving side by side, close together and parallel, tend to be drawn towards each other. What is the reason?
Correct answer A. Water between them moves faster, so the pressure there is lower
Topic / 30 questions
Fluid Dynamics MCQs
Fluid Dynamics MCQs cover fluid drag and terminal velocity, steady and turbulent flow, the equation of continuity and Bernoulli's equation, including its application to blood flow. They help MDCAT, ECAT and FSc candidates revise both theory and calculations, and every question on MCQs360 shows its correct answer instantly.
- Electromagnetic Induction 30
- Fluid Dynamics 30
- Electrostatics 30
- Electronics 30
- Electromagnetism 30
- Current Electricity 30
- Work and Energy 30
- Waves 30
- Vectors and Equilibrium 30
- Nuclear Physics 30
- Dawn of Modern Physics 30
- Thermodynamics 30
- Rotational and Circular Motion 30
- Atomic Spectra 30
- Alternating Current 30
- Force and Motion 30
A Venturi meter fitted in a horizontal pipe is used to measure ____.
Correct answer C. the speed of flow of a fluid
When an artery is narrowed by plaque deposits, how do blood speed and blood pressure change in the narrowed region?
Correct answer C. Speed increases and pressure decreases
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Which explanation best accounts for the lift on an aeroplane wing?
Correct answer C. Air flows faster over the upper surface, so the pressure there is lower than below
Wind blows at 30 m/s over a flat roof of area 100 m² while the air inside is still. What is the approximate upward force on the roof (density of air = 1.2 kg/m³)?
Correct answer D. 5.4 × 10⁴ N
Water at pressure 1.200 × 10⁵ Pa flows at 1.0 m/s in a horizontal pipe of area 10 cm², which narrows to 5.0 cm². What is the pressure in the narrow part (density of water = 1000 kg/m³)?
Correct answer C. 1.185 × 10⁵ Pa
Water flows through a horizontal pipe, with speeds of 2.0 m/s at point X and 4.0 m/s at point Y. What is the pressure difference between X and Y (density of water = 1000 kg/m³)?
Correct answer C. 6.0 kPa
For an ideal fluid flowing through a horizontal pipe of varying cross-section, where is the pressure lowest?
Correct answer B. Where the cross-section is narrowest
The equation of continuity A₁v₁ = A₂v₂ for an incompressible fluid is a consequence of the conservation of ____.
Correct answer C. mass
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Bernoulli’s equation for a fluid flowing along a streamline is based on the principle of conservation of ____.
Correct answer B. energy
Why does a stream of water falling from a tap become narrower as it falls?
Correct answer D. Its speed increases, so by continuity its cross-sectional area must decrease
Blood flows through an aorta of cross-sectional area 3.0 cm² at an average speed of 0.30 m/s. What is the volume flow rate?
Correct answer D. 90 cm³/s
A garden hose of internal radius 1.0 cm delivers water at 2.0 m/s. Approximately how long does it take to fill a 30 L bucket?
Correct answer A. 48 s
Water moves at 0.80 m/s in a pipe of diameter 4.0 cm. What is its speed where the diameter reduces to 2.0 cm?
Correct answer A. 3.2 m/s
Water flows at 1.5 m/s through a pipe of cross-sectional area 8.0 cm² which narrows to 2.0 cm². What is the speed of the water in the narrow section?
Correct answer A. 6.0 m/s
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What is the SI unit of the coefficient of viscosity?
Correct answer B. N s m⁻²
How does the viscosity of most liquids change as their temperature rises?
Correct answer C. It decreases
Which feature is characteristic of turbulent flow?
Correct answer C. Irregular, changing motion with eddies and whirlpools
Laminar flow of a liquid through a pipe tends to become turbulent when ____.
Correct answer D. the flow speed exceeds a certain critical value
Which of the following is NOT an assumption made for an ideal fluid?
Correct answer A. Its density changes noticeably with pressure
About Fluid Dynamics MCQs
The first group of questions deals with viscous drag: Stokes' law for a small sphere, how a falling body reaches terminal velocity, and how shape changes it, as for a skydiver. Questions then describe ideal fluid flow (steady, incompressible and non-viscous) and the change from laminar to turbulent flow. The equation of continuity is linked to conservation of mass, and Bernoulli's equation for a horizontal tube is used to find pressure differences from speeds. Applications include the Bernoulli effect and the speed and pressure of blood in narrowed arteries.
Key facts to remember
- Stokes' law: the drag on a small sphere moving slowly through a fluid is F = 6πηrv.
- Terminal velocity is reached when drag plus upthrust equals weight, so the net force and acceleration are zero.
- Equation of continuity: A₁v₁ = A₂v₂ for an incompressible fluid, a result of conservation of mass.
- Bernoulli's equation: P + ½ρv² + ρgh = constant along a streamline, a result of conservation of energy.
- In a horizontal pipe, P₁ − P₂ = ½ρ(v₂² − v₁²), so pressure is lower where speed is higher.
- In a narrowed artery, blood speed increases and pressure falls in the narrow section.
Exams that include Fluid Dynamics MCQs
Pakistan
- MDCAT
- ECAT (UET)
- NUMS
- AKU
- FSc boards
India
- NEET
- JEE Main
Bangladesh
- HSC
- Medical Admission Test
How to prepare for Fluid Dynamics MCQs
- Link continuity and Bernoulli: a narrower section means faster flow, and faster flow means lower pressure.
- For terminal velocity questions, write out the forces on the body before choosing an answer.
- Learn which quantities appear in Stokes' law (η, r, v) so you can spot the odd one out.
- Practise pressure-difference calculations with ρ = 1000 kg/m³ for water.
Frequently asked questions
Which exams ask Fluid Dynamics MCQs?
Fluid Dynamics is part of the FSc physics syllabus, so its MCQs appear in MDCAT, ECAT (UET), NUMS and AKU entry tests and in FSc board papers. Students in India meet the same ideas in NEET and JEE Main, and Bangladeshi students in HSC and the medical admission test.
What does the equation of continuity state?
The equation of continuity states that for steady flow of an incompressible fluid, the product of cross-sectional area and speed is constant: A₁v₁ = A₂v₂. It follows from conservation of mass, so the fluid speeds up where the pipe narrows and slows down where it widens.
Last reviewed October 2026