Chapter-9 Mechanical Properties of Fluids — Online MCQ Test
PHYSICS · Grade 11 · CBSE(NCERT)
Practice Chapter-9 Mechanical Properties of Fluids with a free chapter-wise online MCQ test.
This chapter covers: Pressure due to a fluid column - Pascal's law - Buoyancy - Streamline flow - Turbulent flow - Critical velocity - Bernoulli's principle - Viscosity - Stokes' law - Terminal velocit....
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter-9 Mechanical Properties of Fluids — Important Questions & Answers
What is the SI unit of pressure?
- A. Newton per square meter (N/m²) or Pascal (Pa)
- B. Dyne per square centimeter
- C. Kilogram per square meter
- D. Joule per cubic meter
Answer: A. Newton per square meter (N/m²) or Pascal (Pa)
The SI unit of pressure is Pascal (Pa), which is equivalent to Newton per square meter (N/m²).
The SI unit of pressure is Pascal (Pa), which is equivalent to Newton per square meter (N/m²).
State Pascal's Law.
- A. Pressure exerted on a confined fluid is transmitted undiminished in all directions
- B. The density of a fluid increases with depth
- C. The buoyant force equals half the weight of the displaced fluid
- D. Viscosity increases with temperature in all fluids
Answer: A. Pressure exerted on a confined fluid is transmitted undiminished in all directions
Pascal's Law states that pressure applied to an enclosed fluid is transmitted equally in all directions with the same magnitude.
Pascal's Law states that pressure applied to an enclosed fluid is transmitted equally in all directions with the same magnitude.
Define buoyancy.
- A. The upward force exerted by a fluid on an object immersed in it
- B. The downward force due to gravity on a submerged object
- C. The resistance offered by a fluid to motion
- D. The property of a liquid to form drops
Answer: A. The upward force exerted by a fluid on an object immersed in it
Buoyancy is the upward force experienced by an object immersed in a fluid, arising from the pressure difference.
Buoyancy is the upward force experienced by an object immersed in a fluid, arising from the pressure difference.
What is Archimedes' Principle?
- A. The buoyant force on an object equals the weight of the fluid displaced by it
- B. The pressure at the bottom of a container depends on the shape of the container
- C. Surface tension is inversely proportional to temperature
- D. The viscosity of a fluid is independent of temperature
Answer: A. The buoyant force on an object equals the weight of the fluid displaced by it
Archimedes' Principle states that the buoyant force is equal to the weight of the fluid displaced by the immersed object.
Archimedes' Principle states that the buoyant force is equal to the weight of the fluid displaced by the immersed object.
A hydraulic press applies Pascal's Law. If the input piston has area A₁ and output piston has area A₂ (where A₂ > A₁), and a force F₁ is applied to the input piston, what is the output force F₂?
- A. F₂ = F₁(A₂/A₁)
- B. F₂ = F₁(A₁/A₂)
- C. F₂ = F₁A₁A₂
- D. F₂ = F₁/(A₁A₂)
Answer: A. F₂ = F₁(A₂/A₁)
By Pascal's Law, pressure is constant: F₁/A₁ = F₂/A₂, so F₂ = F₁(A₂/A₁), giving mechanical advantage.
By Pascal's Law, pressure is constant: F₁/A₁ = F₂/A₂, so F₂ = F₁(A₂/A₁), giving mechanical advantage.
A metal sphere is immersed in a fluid. Which factor does NOT affect the buoyant force?
- A. The density of the sphere material
- B. The volume of the sphere
- C. The density of the fluid
- D. The acceleration due to gravity
Answer: A. The density of the sphere material
Buoyant force F_b = ρ_fluid × V × g. It depends on fluid density, volume displaced, and gravity—not on the material density of the object.
Buoyant force F_b = ρ_fluid × V × g. It depends on fluid density, volume displaced, and gravity—not on the material density of the object.
A spherical ball of density ρ_ball and radius r falls through a fluid of density ρ_fluid and viscosity η. Assuming Stokes' Law applies and terminal velocity is reached, the terminal velocity is proportional to which of the following?
- A. r² and (ρ_ball - ρ_fluid)
- B. r and η
- C. r⁻² and ρ_fluid
- D. r⁴ and (ρ_ball + ρ_fluid)
Answer: A. r² and (ρ_ball - ρ_fluid)
From mg = 6πηrv_t, we get v_t = [2r²g(ρ_ball - ρ_fluid)]/(9η), showing v_t ∝ r² and (ρ_ball - ρ_fluid).
From mg = 6πηrv_t, we get v_t = [2r²g(ρ_ball - ρ_fluid)]/(9η), showing v_t ∝ r² and (ρ_ball - ρ_fluid).
Bernoulli's principle is applied to a horizontal pipe where water flows from a wider section (area A₁) to a narrower section (area A₂). How do the pressures in the two sections compare?
- A. Pressure is higher in the narrower section
- B. Pressure is higher in the wider section
- C. Pressures are equal in both sections
- D. The relationship depends on the viscosity of water
Answer: B. Pressure is higher in the wider section
By Bernoulli's principle: P₁ + ½ρv₁² = P₂ + ½ρv₂². Since v₂ > v₁ (due to continuity), P₁ > P₂, so pressure is higher in the wider section.
By Bernoulli's principle: P₁ + ½ρv₁² = P₂ + ½ρv₂². Since v₂ > v₁ (due to continuity), P₁ > P₂, so pressure is higher in the wider section.
A student uses Bernoulli's equation to explain why a spinning cricket ball curves in flight. Which assumption in the standard derivation of Bernoulli's equation is violated in this scenario, making the simple analysis invalid?
- A. The assumption of inviscid (frictionless) flow; viscosity and boundary layer effects are crucial for the Magnus effect
- B. The assumption of incompressible flow
- C. The assumption that flow is irrotational
- D. The assumption that pressure is constant along a streamline
Answer: A. The assumption of inviscid (frictionless) flow; viscosity and boundary layer effects are crucial for the Magnus effect
Bernoulli's equation assumes inviscid flow. The Magnus effect (ball curving) arises from viscous effects creating an asymmetric boundary layer around the spinning ball, which simple Bernoulli analysis cannot explain.
Bernoulli's equation assumes inviscid flow. The Magnus effect (ball curving) arises from viscous effects creating an asymmetric boundary layer around the spinning ball, which simple Bernoulli analysis cannot explain.
A capillary tube is inverted and held vertically with its open end submerged in a container of liquid. The capillary rises to height h above the liquid surface. If the same capillary tube is now held at an angle θ to the vertical, what is the new height of rise along the tube's length?
- A. h/cosθ
- B. h·cosθ
- C. h·sinθ
- D. h·tanθ
Answer: A. h/cosθ
The vertical height of rise remains h (determined by pressure balance), but the length along the inclined tube becomes h/cosθ. The capillary rise along the tube is h/cosθ.
The vertical height of rise remains h (determined by pressure balance), but the length along the inclined tube becomes h/cosθ. The capillary rise along the tube is h/cosθ.