Mechanical Engineering Flashcards
6 cards from real BE/B Eng Bachelor of Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Mechanical Engineering flashcards as text
Which law of thermodynamics states that energy cannot be created or destroyed, only converted from one form to another?
Answer: First Law
The First Law of Thermodynamics is the law of energy conservation: the total energy of an isolated system remains constant.
What does the second law of thermodynamics imply about the entropy of an isolated system?
Answer: Entropy always increases or remains constant
The Second Law states that the entropy of an isolated system tends to increase over time, indicating the direction of spontaneous processes.
In stress-strain analysis, Young's Modulus is defined as the ratio of:
Answer: Stress to strain in the elastic region
Young's Modulus (E) = σ/ε, where σ is axial stress and ε is axial strain, applicable within the linear elastic region of a material.
What is the efficiency of an ideal Carnot heat engine operating between temperatures T_H = 600 K and T_C = 300 K?
Answer: 50%
Carnot efficiency η = 1 - T_C/T_H = 1 - 300/600 = 0.50, or 50%; no real engine can exceed this limit between these temperatures.
Which type of stress acts perpendicular to the cross-sectional area of a member?
Answer: Normal stress
Normal stress (σ = F/A) acts perpendicular (normal) to the cross-section, either as tension (pulling) or compression (pushing).
In fluid mechanics, what does the Reynolds number represent?
Answer: The ratio of inertial forces to viscous forces in a fluid flow
The Reynolds number (Re = ρVL/μ) indicates whether a flow is laminar (low Re) or turbulent (high Re) by comparing inertial and viscous forces.