Which of the following fluids is classified as non-Newtonian?

The correct answer is C: Ketchup. Ketchup is a pseudoplastic fluid whose viscosity changes with shear rate. Water, air, and mercury are Newtonian fluids with constant viscosity.

In fluid mechanics, which of the following statements about Pascal's law is correct?

The correct answer is A: Pressure applied to a confined fluid is transmitted equally in all directions. Pascal's law states that pressure applied to a confined fluid is transmitted undiminished in all directions. This principle is fundamental to hydraulic systems used in Indian industries.

For a polytropic process PVⁿ = constant with n=1.3 for an ideal gas, if initial state is (P₁=1 bar, T₁=300 K) and final pressure P₂=4 bar, the final temperature is approximately:

The correct answer is B: 520 K. Using PVⁿ = const and ideal gas law: T₂/T₁ = (P₂/P₁)^((n-1)/n) = 4^(0.3/1.3) ≈ 1.733, so T₂ ≈ 520 K

A substance has a critical temperature Tc=647 K and critical pressure Pc=22.1 MPa. This is most likely:

The correct answer is B: Water. These are the critical constants for water. This falls within standard thermodynamic property tables for water.

In a sliding contact bearing, which parameter represents the bearing characteristic number?

The correct answer is A: λ = μN/P (Sommerfeld number). The Sommerfeld number λ = μN/P is the primary bearing characteristic number used in hydrodynamic bearing analysis.

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Mechanical Engineering
Fluid Mechanics

Thermodynamics, hydraulics, machine design

37 Q 3 Topics Take Mock Test

Difficulty: All Easy Medium Hard 11–20 of 37

Topics in Mechanical Engineering

All Thermodynamics 100 Fluid Mechanics 79 Machine Design 80

Q.11 Medium Fluid Mechanics

A 100 mm diameter pipe contains a 90° elbow. If water flows at 3 m/s and minor loss coefficient K = 0.9, what is the head loss?

A 0.123 m

B 0.205 m

C 0.369 m

D 0.410 m

Correct Answer: C. 0.369 m

EXPLANATION

h_minor = K(V²/2g) = 0.9 × (9/19.62) = 0.369 m

Test

Q.12 Medium Fluid Mechanics

Which dimensionless number is used to characterize the relative importance of gravity and inertial forces in open channel flow?

A Reynolds number

B Froude number

C Strouhal number

D Weber number

Correct Answer: B. Froude number

EXPLANATION

The Froude number Fr = V/√(gD_h) characterizes gravity effects. In open channel flow, it determines flow regime (subcritical Fr<1, supercritical Fr>1).

Test

Q.13 Medium Fluid Mechanics

A jet of water with velocity 20 m/s hits a flat plate perpendicularly. If the jet diameter is 50 mm and density is 1000 kg/m³, what is the force exerted on the plate?

A 3927 N

B 7854 N

C 1963 N

D 5891 N

Correct Answer: A. 3927 N

EXPLANATION

Force F = ρAV² = 1000 × (π × 0.025²) × 20² = 1000 × 0.001963 × 400 = 3927 N

Test

Q.14 Medium Fluid Mechanics

A turbine receives water at 3.5 m³/s with a head of 45 m. If the turbine efficiency is 85%, what is the power output?

A 1312 kW

B 1543 kW

C 1863 kW

D 1680 kW

Correct Answer: A. 1312 kW

EXPLANATION

Power output = η × ρgQH = 0.85 × 1000 × 9.81 × 3.5 × 45 = 1312 kW approximately

Test

Q.15 Medium Fluid Mechanics

A pump delivers 0.05 m³/s of water against a head of 25 m. If the pump efficiency is 80%, what is the required power input?

A 15.31 kW

B 12.25 kW

C 10.20 kW

D 20.40 kW

Correct Answer: A. 15.31 kW

EXPLANATION

Hydraulic power = ρgQH = 1000 × 9.81 × 0.05 × 25 = 12.26 kW. Required power = 12.26/0.80 = 15.33 kW

Test

Q.16 Medium Fluid Mechanics

A submerged orifice discharges water under a head of 4 m. The coefficient of discharge is 0.62. If the orifice area is 0.01 m², what is the discharge rate?

A 0.0124 m³/s

B 0.0248 m³/s

C 0.0372 m³/s

D 0.0496 m³/s

Correct Answer: A. 0.0124 m³/s

EXPLANATION

Q = Cd × A × √(2gh) = 0.62 × 0.01 × √(2 × 9.81 × 4) = 0.0124 m³/s

Test

Q.17 Medium Fluid Mechanics

In a pitot tube measurement, the stagnation pressure is 105.5 kPa and static pressure is 100 kPa. What is the velocity of the fluid? (ρ = 1000 kg/m³)

A 3.16 m/s

B 5.24 m/s

C 10.48 m/s

D 2.25 m/s

Correct Answer: A. 3.16 m/s

EXPLANATION

Using Bernoulli: (P₀ - P) = ½ρV². So V = √(2 × 5500/1000) = 3.32 m/s ≈ 3.16 m/s

Test

Q.18 Medium Fluid Mechanics

A horizontal pipe of diameter 50 mm carries water at 2 m/s. If the pipe length is 100 m and friction factor f = 0.04, calculate the head loss using Darcy-Weisbach equation.

A 3.27 m

B 6.53 m

C 1.63 m

D 8.16 m

Correct Answer: B. 6.53 m

EXPLANATION

hf = f(L/D)(V²/2g) = 0.04 × (100/0.05) × (4/19.62) = 6.53 m

Test

Q.19 Medium Fluid Mechanics

For water flow in a pump system, cavitation occurs when:

A Pressure exceeds saturation pressure

B Pressure falls below vapor pressure

C Velocity becomes very high

D Temperature increases significantly

Correct Answer: B. Pressure falls below vapor pressure

EXPLANATION

Cavitation occurs when local pressure drops below fluid vapor pressure, causing vapor bubbles to form.

Test

Q.20 Medium Fluid Mechanics

The Mach number M = 0.3 indicates:

A Compressible flow effects are significant

B Incompressible flow assumption is valid

C Supersonic flow regime

D Shock waves will form

Correct Answer: B. Incompressible flow assumption is valid

EXPLANATION

M < 0.3 indicates incompressible flow approximation is valid; compressibility effects are negligible.

Test

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