Home Subjects Mechanical Engineering Fluid Mechanics

Mechanical Engineering
Fluid Mechanics

Thermodynamics, hydraulics, machine design

79 Q 2 Topics Take Test
Advertisement
Difficulty: All Easy Medium Hard 41–50 of 79
Topics in Mechanical Engineering
All Thermodynamics 100 Fluid Mechanics 79
Q.41 Easy Fluid Mechanics
A fluid undergoes viscous deformation with velocity gradient du/dy = 50 s⁻¹. For Newtonian fluid with μ = 0.1 Pa·s, the shear stress is:
A 5 Pa
B 500 Pa
C 5000 Pa
D 0.002 Pa
Correct Answer:  A. 5 Pa
EXPLANATION

τ = μ(du/dy) = 0.1 × 50 = 5 Pa

Take Test
Q.42 Easy Fluid Mechanics
For steady flow of an incompressible fluid through a variable area duct, which equation relates velocities at different sections?
A Bernoulli equation
B Continuity equation (A₁v₁ = A₂v₂)
C Energy equation
D Momentum equation
Correct Answer:  B. Continuity equation (A₁v₁ = A₂v₂)
EXPLANATION

Continuity equation for incompressible flow states Q = constant, so A₁v₁ = A₂v₂

Take Test
Q.43 Hard Fluid Mechanics
In a centrifugal pump, the impeller diameter is doubled while keeping speed constant. The head capacity changes by factor of:
A 2
B 4
C 8
D √2
Correct Answer:  B. 4
EXPLANATION

Head H ∝ D²N² at constant N, so head increases by 2² = 4 times

Take Test
Q.44 Hard Fluid Mechanics
The equivalent length method for minor losses in pipes replaces a fitting with an equivalent length of pipe. For a 90° elbow with diameter 50 mm, typical equivalent length is:
A 0.5 m
B 1.0 m
C 2.0-3.0 m
D 5.0 m
Correct Answer:  C. 2.0-3.0 m
EXPLANATION

Equivalent length L_e = K × (d/f) ≈ 0.9 × (0.05/0.02) ≈ 2.25 m for typical elbow

Take Test
Q.45 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.

Take Test
Q.46 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.

Take Test
Q.47 Hard Fluid Mechanics
For a submerged curved vane deflecting a jet, the component of force in the direction of jet is:
A ρQ²/A
B ρQv(1 - cos θ)
C ρQv cos θ
D ρQv sin θ
Correct Answer:  B. ρQv(1 - cos θ)
EXPLANATION

Force component = ρQv(1 - cos θ) where θ is deflection angle from momentum equation.

Take Test
Q.48 Medium Fluid Mechanics
A pipeline carrying oil (ν = 2 × 10⁻⁴ m²/s) has diameter 0.5 m and velocity 2 m/s. The flow regime is:
A Laminar (Re < 2300)
B Transitional (2300 < Re < 4000)
C Turbulent (Re > 4000)
D Cannot be determined
Correct Answer:  C. Turbulent (Re > 4000)
EXPLANATION

Re = vd/ν = (2 × 0.5)/(2 × 10⁻⁴) = 5000 > 4000, so turbulent

Take Test
Q.49 Hard Fluid Mechanics
In open channel flow, the critical depth occurs when:
A Froude number = 0
B Froude number = 1
C Reynolds number = 500
D Velocity = maximum
Correct Answer:  B. Froude number = 1
EXPLANATION

Critical depth in open channel flow corresponds to Fr = 1, minimum specific energy condition.

Take Test
Q.50 Medium Fluid Mechanics
The Froude number characterizes the relative importance of:
A Inertial forces to viscous forces
B Inertial forces to gravitational forces
C Surface tension to inertial forces
D Pressure forces to elastic forces
Correct Answer:  B. Inertial forces to gravitational forces
EXPLANATION

Fr = v/√(gL) compares inertial forces (ρv²) with gravitational forces (ρgL).

Take Test
IGET
iget AI
Online · Ask anything about exams
Hi! 👋 I'm your iget AI assistant.

Ask me anything about exam prep, MCQ solutions, study tips, or strategies! 🎯
UPSC strategy SSC CGL syllabus Improve aptitude NEET Biology tips