Pascal (Pa) is equal to:
- N/m
- N/m²
- N²/m²
- kg/m
Show answer and explanation
Answer: B. N/m²
Pressure = Force/Area, so its SI unit pascal (Pa) = N/m².
FSC Physics: Fluid Dynamics, questions with answers
Practise 27 real Federal Board questions on Fluid Dynamics from 2023 to 2026. See the answer and explanation as soon as you answer.
27real questions
8multiple choice
5exam sessions
About Fluid Dynamics in FSC Physics
Fluid Dynamics is one of the 14 main chapters in our Federal Board FSC Physics question bank (11th and 12th class), and about 5% of its real questions come from it. Tayyari Karo has 27 real questions on this chapter from 2023 to 2026; 8 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 20 medium, 7 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 8 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
In a steady, incompressible flow, if the cross-sectional area of a pipe decreases to one-third of its original size, what happens to the fluid velocity?
- It decreases to one-third
- It remains the same
- It triples
- It becomes nine times larger
Show answer and explanation
Answer: C. It triples
By the equation of continuity A₁v₁=A₂v₂, if area becomes A/3, velocity must triple to keep the flow rate constant.
Maximum drag force on a 1 kg falling sphere is:
- 9.8 N
- 1 N
- 98 N
- 4.9 N
Show answer and explanation
Answer: A. 9.8 N
At terminal velocity, drag force balances weight: F_drag(max) = mg = 1 × 9.8 = 9.8 N.
Young's Modulus, Y =
- (ΔL/L)/(F/A)
- FA/(ΔL.L)
- (ΔL.L)/(FA)
- (F/A)/(ΔL/L)
Show answer and explanation
Answer: D. (F/A)/(ΔL/L)
Y = stress/strain = (F/A)/(ΔL/L).
Which of the following devices is used to measure speed of liquid flow?
- Barometer
- Venturimeter
- Spectrometer
- Speedometer
Show answer and explanation
Answer: B. Venturimeter
A venturimeter uses the pressure difference (Bernoulli's principle) in a constricted tube to measure the flow speed of a liquid.
A wire is stretched to double of its length; its strain is:
- 0.5
- 0
- 2
- 1
Show answer and explanation
Answer: D. 1
Strain = ΔL/L = (2L − L)/L = L/L = 1.
Distinguish between turbulent and streamline flow.
Show model answer
Streamline (laminar) flow: fluid particles move in smooth, well-defined, non-crossing paths (streamlines), typically at low speeds; the flow is orderly and predictable, occurring below a critical velocity.
Turbulent flow: fluid particles move in irregular, chaotic paths with eddies and vortices, typically at high speeds (above the critical velocity); the flow is disorderly and unpredictable, and streamlines cross and mix.
A 300 kg load produces an extension 0.2 cm in a steel wire having length 2.0 m and cross-sectional area 15 cm². Determine: a) Stress b) Strain c) Young's Modulus for Steel (Y).
Show model answer
F = mg = 300 × 9.8 = 2940 N. A = 15 cm² = 1.5×10⁻³ m². ΔL = 0.2 cm = 0.002 m. L = 2.0 m.
a) Stress = F/A = 2940/(1.5×10⁻³) ≈ 1.96×10⁶ Pa
b) Strain = ΔL/L = 0.002/2.0 = 1×10⁻³ (dimensionless)
c) Y = stress/strain = (1.96×10⁶)/(1×10⁻³) ≈ 1.96×10⁹ Pa
Sessions with Fluid Dynamics questions
| Session | Questions |
|---|---|
| 2026 Annual | 6 |
| 2025 1st Annual | 10 |
| 2025 2nd Annual | 2 |
| 2024 Annual | 5 |
| 2023 Annual | 4 |
Common questions
What does the Fluid Dynamics chapter cover on this page?
27 real Federal Board (FBISE) Physics questions on Fluid Dynamics from 2023 to 2026, for 11th and 12th class. Each one shows the session it came from.
Are the answers official?
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
Is it free?
You can start free with no signup. A small set of papers per subject is free, and Premium unlocks the full question bank.