Water Resources · MCQ practice Properties of Fluid MCQs – Part 4
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Part 4 of 6 Question 46 Easy
The compressibility of the fluid is given as 5 × 10⁻¹¹ Pa⁻¹. What is the Bulk modulus (GPa) of fluid?
A 10 B 15 C 20 D 25
Answer: C. 20
Bulk modulus K = 1 / β = 1 / (5 × 10⁻¹¹ Pa⁻¹) = 2 × 10¹⁰ Pa = 20 GPa.
Question 47 Easy
Which one of the following is true about ideal fluid?
A It is compressible B It is incompressible C It has high shear force D It has high value of viscosity
Answer: B. It is incompressible
An ideal fluid is assumed to be incompressible (constant density) and non-viscous (zero viscosity).
Question 48 Medium
The diameter of droplet is 0.075 mm. What is the intensity of the pressure (N/sq. cm) developed in the droplet by surface of 0.000075 N/mm?
A 0.4 B 0.6 C 0.8 D 1
Answer: A. 0.4
Excess pressure in a droplet is p = 4σ / d = 4 × 0.000075 / 0.075 = 0.004 N/mm² = 0.4 N/cm².
Question 49 Easy
Which of the following is CORRECT about the viscosity of gas?
A Inversely proportional to the temperature B Increases with an increase in the temperature C Independent of pressure D Independent of temperature
Answer: B. Increases with an increase in the temperature
The viscosity of a gas increases with temperature because thermal agitation increases molecular collisions and momentum transfer.
Question 50 Medium
Apart from inertial force, which of the following forces is most important in motion of submarines under water?
A Viscous force B Gravity force C Compressive force D Surface tension force
Answer: A. Viscous force
For deeply submerged bodies like submarines away from free surfaces, viscous shear drag dominates, governed by Reynolds number.
Question 51 Easy
If the diameter of a capillary tube is doubled, the capillary rise will be:
A Unaffected B Doubled C Halfed D None of the above
Answer: C. Halfed
Capillary rise h is inversely proportional to tube diameter d (h ∝ 1/d). Doubling the diameter halves the capillary rise.
Question 52 Easy
Surface tension has the dimensions:
A F L⁻¹ B F C F L⁻² D F L⁻³
Answer: A. F L⁻¹
Surface tension is force per unit length: [F] / [L] = [F L⁻¹] (or [M T⁻²] in mass base units).
Question 53 Easy
Newton's law of viscosity is a relationship between:
A Pressure, velocity and temperature B Rate of shear strain and temperature C Shear stress and velocity D Shear stress and rate of shear strain
Answer: D. Shear stress and rate of shear strain
Newton's law relates shear stress τ directly to the rate of shear strain du/dy: τ = μ(du/dy).
Question 54 Easy
Stoke is the unit of:
A Dynamic viscosity B Kinematic viscosity C Specific volume D Specific weight
Answer: B. Kinematic viscosity
The stoke (cm²/s) is the CGS unit of kinematic viscosity (1 stoke = 10⁻⁴ m²/s).
Question 55 Easy
In a Newtonian fluid:
A The shear stress is directly proportional to the rate of fluid deformation B Dynamic viscosity is directly proportional to the rate of fluid deformation C Kinematic viscosity is directly proportional to the rate of fluid deformation D Dynamic viscosity is zero
Answer: A. The shear stress is directly proportional to the rate of fluid deformation
In a Newtonian fluid, dynamic viscosity remains constant and shear stress is directly proportional to the rate of shear deformation.
Question 56 Easy
The difference of pressure between the inside and outside of a liquid drop is:
A p = T × r B p = T / r C p = T / 2r D p = 2T / r
Answer: D. p = 2T / r
For a liquid droplet of radius r, equilibrium gives p·πr² = T·2πr, so p = 2T / r (or 4T / d).
Question 57 Easy
The property by which a liquid opposes relative motion between its different layers is called:
A surface tension B co-efficient of viscosity C viscosity D osmosis
Answer: C. viscosity
Viscosity is the intrinsic property of a fluid by virtue of which it offers internal friction to relative motion between adjacent layers.
Question 58 Easy
If 850 kg liquid occupies volume of one cubic meter, then 0.85 represents its:
A Specific weight B Specific mass C Specific gravity D Specific density
Answer: C. Specific gravity
Density is 850 kg/m³. Dividing by standard water density (1000 kg/m³) gives 0.85, which represents its specific gravity.
Question 59 Easy
A liquid would wet the solid, if adhesion forces as compared to cohesion force are:
A Less B More C Equal D Less at low temperature and more at high temperature
Answer: B. More
A liquid wets a solid surface when adhesive forces between liquid and solid molecules exceed cohesive forces within the liquid (contact angle θ < 90°).
Question 60 Medium
The Value of mass density in kg·sec²/m⁴ for water at 0°C is:
A 1 B 1000 C 100 D 101.9
Answer: D. 101.9
In gravitational MKS engineering units, mass density is ρ = γ / g = 1000 kgf/m³ / 9.81 m/s² = 101.9 kg·s²/m⁴.
Part 4 of 6