Description: Practice Class 11 Physics Chapter 6 Fluid Mechanics MCQs according to the FBISE HSSC-I syllabus. These exam-oriented questions cover pressure, density, Pascal’s principle, Archimedes’ principle, flotation, fluid flow, continuity equation, Bernoulli’s principle, viscosity, surface tension, capillary action and terminal velocity.
1. The branch of physics that deals with fluids at rest and in motion is called:
A) thermodynamics B) mechanics of solids C) fluid mechanics D) optics
2. A fluid is a substance that can:
A) flow and change shape continuously under shear stress B) resist all deformation C) maintain a fixed shape D) have zero mass
3. The SI unit of pressure is:
A) newton B) pascal C) joule D) watt
4. Pressure is defined as force acting normally per unit:
A) volume B) mass C) length D) area
5. The pressure exerted by a fluid at rest increases with:
A) depth B) surface area only C) temperature only D) height above the surface
6. The pressure at a depth h in a liquid of density ρ is given by:
A) P = ρ/hg B) P = h/ρg C) P = ρgh D) P = ρg/h
7. The pressure due to a liquid column depends directly on its:
A) shape of container B) density C) surface area only D) colour
8. At the same depth in a liquid at rest, pressure is:
A) greater in a narrow vessel B) greater in a wide vessel C) zero at the walls D) the same in all directions
9. Atmospheric pressure is caused mainly by the:
A) weight of the atmosphere B) rotation of Earth only C) temperature of oceans D) magnetic field
10. A barometer is used to measure:
A) density B) surface tension C) atmospheric pressure D) viscosity
11. Standard atmospheric pressure is approximately:
A) 1.013 × 10^3 Pa B) 1.013 × 10^5 Pa C) 1.013 × 10^7 Pa D) 1.013 × 10^9 Pa
12. A hydraulic press works on:
A) Bernoulli's principle B) Archimedes' principle C) law of conservation of momentum D) Pascal's principle
13. Pascal's principle states that pressure applied to an enclosed fluid is transmitted:
A) undiminished in all directions B) only downward C) only upward D) only to the nearest wall
14. A hydraulic machine can multiply force because the output piston can have a larger:
A) density B) pressure C) area D) mass
15. If the area of the output piston is four times the input piston, the ideal output force is:
A) one-fourth of input force B) four times input force C) twice input force D) unchanged
16. The upward force exerted by a fluid on an immersed object is called:
A) friction B) tension C) weight D) buoyant force
17. Archimedes' principle states that the buoyant force equals the:
A) weight of fluid displaced B) mass of the object C) volume of the object D) weight of the object
18. An object floats in a liquid when its average density is:
A) greater than the liquid density B) equal to zero C) less than or equal to the liquid density D) always greater than air density
19. A body completely immersed in a fluid experiences buoyant force that depends on the:
A) colour of body B) volume of fluid displaced C) shape of the container only D) mass of the container
20. A ship made of steel floats because its average density is:
A) greater than water B) equal to steel density C) zero D) less than water
21. The principle of flotation states that a floating body displaces a liquid whose weight is:
A) equal to the weight of the body B) greater than the body C) less than the body D) zero
22. The density of a substance is defined as its mass per unit:
A) area B) length C) volume D) pressure
23. The SI unit of density is:
A) g/cm³ B) kg/m³ C) kg/m² D) N/m³
24. Specific gravity is the ratio of the density of a substance to the density of:
A) air B) mercury C) oil D) water
25. An object sinks in water if its average density is:
A) greater than the density of water B) less than the density of water C) zero D) equal to air density
26. Fluid flow in which each particle follows a smooth path without irregular mixing is called:
A) turbulent flow B) random flow C) streamline flow D) rotational flow
27. In steady flow, the velocity of a fluid at a given point:
A) changes randomly with time B) remains constant with time C) is always zero D) must be equal to pressure
28. The equation of continuity for an incompressible fluid is:
A) P₁V₁ = P₂V₂ B) F₁A₁ = F₂A₂ C) ρ₁V₁ = ρ₂V₂ D) A₁v₁ = A₂v₂
29. When the cross-sectional area of a pipe decreases, the speed of an incompressible fluid generally:
A) increases B) decreases C) becomes zero D) remains necessarily unchanged
30. The continuity equation is based on conservation of:
A) energy B) momentum C) mass D) pressure
31. Bernoulli's equation for steady ideal fluid flow expresses conservation of:
A) mass only B) mechanical energy C) electric charge D) temperature
32. According to Bernoulli's principle, where fluid speed is high, pressure is generally:
A) high B) constant C) zero D) low
33. For an ideal fluid, Bernoulli's equation is based on the assumptions of steady, incompressible and:
A) non-viscous flow B) highly turbulent flow C) compressible flow D) zero-density flow
34. An airplane wing produces lift partly because of:
A) Pascal's principle only B) Archimedes' principle only C) pressure differences associated with airflow D) atmospheric pressure being zero
35. A perfume atomizer works mainly using the:
A) law of inertia B) Bernoulli effect C) law of reflection D) principle of moments
36. When air moves rapidly over the top of a suitable aerofoil, the pressure there can become:
A) greater than below B) equal to vacuum C) unrelated to speed D) lower than below
37. Viscosity is the property of a fluid that measures its resistance to:
A) flow or relative motion between layers B) compression only C) gravity D) buoyancy
38. The SI unit of dynamic viscosity is:
A) newton B) pascal C) Pa·s D) joule
39. Honey has a greater viscosity than water. Therefore honey:
A) flows more easily B) offers greater resistance to flow C) has zero density D) has no internal friction
40. For laminar flow through a narrow tube, increasing viscosity while other factors remain constant generally:
A) increases flow rate B) has no effect C) makes pressure zero D) decreases flow rate
41. Surface tension is caused by:
A) cohesive forces between liquid molecules B) gravitational force alone C) magnetic force D) nuclear force
42. Surface tension tends to make a liquid surface behave like a:
A) rigid solid B) vacuum C) stretched elastic membrane D) gas with no surface
43. A liquid drop tends to become spherical mainly because surface tension:
A) increases its volume B) minimizes surface area C) eliminates gravity D) increases its mass
44. Capillary action is the rise or fall of a liquid in a narrow tube due mainly to:
A) pressure from the atmosphere only B) density alone C) temperature alone D) adhesive and cohesive forces
45. Water rises in a clean glass capillary because adhesion between water and glass is:
A) strong enough relative to cohesion to cause wetting B) zero C) less than all molecular forces D) unrelated to capillary action
46. A liquid that does not wet the walls of a capillary generally shows:
A) a concave meniscus B) no surface tension C) a convex meniscus D) zero viscosity
47. The pressure inside a liquid droplet is greater than outside because of:
A) gravity alone B) surface tension C) atmospheric oxygen D) buoyant force
48. The flow of a fluid becomes turbulent when its flow speed is sufficiently:
A) low B) zero C) independent of conditions D) high
49. Reynolds number is used to help distinguish between:
A) laminar and turbulent flow B) solid and liquid C) mass and weight D) heat and work
50. The terminal speed of a small sphere falling through a viscous fluid is reached when:
A) its acceleration is maximum B) gravity becomes zero C) net force becomes zero D) buoyant force becomes zero
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Syllabus & SLO Alignment
FBISE syllabus: National Curriculum of Pakistan 2022–23, FBISE Assessment Framework for Physics Grade XI.
Content area: Domain B – Mechanics / Fluid Dynamics
Relevant SLOs: P-11-B-33 to P-11-B-44
Alignment: Archimedes’ principle and flotation; ideal-fluid flow; continuity; Bernoulli’s equation; viscosity; viscous drag; superfluidity and real-world Bernoulli applications.
Assessment note: The FBISE framework distinguishes summative SLOs used in the final examination from formative SLOs used in teaching-learning. MCQs on this page should be treated as practice aligned to the listed content/SLOs, not as a reproduction of the official FBISE paper.