Fundamentals of Engineering Fluid Mechanics and Thermodynamics 2 — Questions and Answers
Question 1: For an ideal gas, which equation relates pressure, volume, temperature, and number of moles?
- PV = nRT (Correct answer)
- PV = nT/R
- P = nRT/V²
- PV² = nRT
Correct answer: PV = nRT
The ideal gas law PV = nRT relates pressure P, volume V, moles n, ideal gas constant R, and temperature T.
Question 2: What is the Carnot efficiency of a heat engine operating between temperatures T_H = 800 K and T_C = 400 K?
- 50% (Correct answer)
- 25%
- 75%
- 100%
Correct answer: 50%
Carnot efficiency η = 1 - T_C/T_H = 1 - 400/800 = 0.50 = 50%.
Question 3: Which fluid property describes resistance to shear deformation (resistance to flow)?
- Dynamic viscosity (Correct answer)
- Density
- Surface tension
- Compressibility
Correct answer: Dynamic viscosity
Dynamic viscosity μ is the property that quantifies a fluid's resistance to shear stress and flow.
Question 4: What is head loss due to friction in a pipe best described by?
- Darcy-Weisbach equation (Correct answer)
- Bernoulli's equation
- Continuity equation
- Manning's equation
Correct answer: Darcy-Weisbach equation
The Darcy-Weisbach equation h_f = f(L/D)(V²/2g) gives the friction head loss in a pipe.
Question 5: What happens to the entropy of a system during a reversible adiabatic process?
- It remains constant (Correct answer)
- It increases
- It decreases
- It fluctuates
Correct answer: It remains constant
A reversible adiabatic (isentropic) process has no heat transfer and no irreversibilities, so entropy remains constant.
Question 6: Buoyancy force on a submerged object equals:
- The weight of fluid displaced by the object (Correct answer)
- The weight of the object itself
- The pressure at the object's centroid times its volume
- The product of object density and gravity
Correct answer: The weight of fluid displaced by the object
Archimedes' principle states that the buoyant force equals the weight of fluid displaced by the submerged object.
Fundamentals of Engineering Fluid Mechanics and Thermodynamics 2
For an ideal gas, which equation relates pressure, volume, temperature, and number of moles?