Fundamentals of Engineering Fluid Mechanics and Thermodynamics 1 — Questions and Answers
Question 1: Bernoulli's equation is derived from conservation of which quantity along a streamline?
- Energy (Correct answer)
- Mass
- Momentum
- Volume
Correct answer: Energy
Bernoulli's equation is an energy conservation equation along a streamline for steady, incompressible, inviscid flow.
Question 2: What is the hydrostatic pressure at a depth h in a fluid of density ρ?
- ρgh (Correct answer)
- ρg/h
- ρ/gh
- gh/ρ
Correct answer: ρgh
Hydrostatic pressure is p = ρgh, where ρ is fluid density, g is gravitational acceleration, and h is depth.
Question 3: The continuity equation for incompressible flow through a pipe states that:
- A₁V₁ = A₂V₂ (Correct answer)
- A₁V₁² = A₂V₂²
- V₁/A₁ = V₂/A₂
- A₁ + V₁ = A₂ + V₂
Correct answer: A₁V₁ = A₂V₂
For incompressible flow, conservation of mass requires A₁V₁ = A₂V₂ (flow rate is constant).
Question 4: Which law of thermodynamics states that energy cannot be created or destroyed, only converted?
- First law of thermodynamics (Correct answer)
- Second law of thermodynamics
- Zeroth law of thermodynamics
- Third law of thermodynamics
Correct answer: First law of thermodynamics
The First Law of Thermodynamics is the law of conservation of energy: ΔU = Q - W.
Question 5: What does the Reynolds number represent in fluid mechanics?
- The ratio of inertial forces to viscous forces (Correct answer)
- The ratio of pressure to density
- The ratio of velocity to acceleration
- The ratio of kinetic to potential energy
Correct answer: The ratio of inertial forces to viscous forces
The Reynolds number Re = ρVD/μ is the ratio of inertial to viscous forces, used to predict flow regime (laminar vs. turbulent).
Question 6: What is the Second Law of Thermodynamics associated with?
- Entropy always increases in an isolated system (Correct answer)
- Energy cannot be converted
- All processes are reversible
- Heat flows from cold to hot spontaneously
Correct answer: Entropy always increases in an isolated system
The Second Law states that entropy of an isolated system always increases, indicating irreversibility of natural processes.
Fundamentals of Engineering Fluid Mechanics and Thermodynamics 1
Bernoulli's equation is derived from conservation of which quantity along a streamline?