Engineering Sciences Flashcards

What is the moment of inertia of a rectangular cross-section about its centroidal axis?

Answer: bh³/12

The second moment of area for a rectangle about its centroidal horizontal axis is I = bh³/12, where b is width and h is height. This is fundamental for beam bending analysis.

Bernoulli's equation assumes:

Answer: Steady, incompressible, inviscid flow along a streamline

Bernoulli's equation (P + ½ρv² + ρgh = constant) applies to steady, incompressible, inviscid flow along a streamline, representing conservation of energy in fluid flow.

The Mohr's circle is used to determine:

Answer: Principal stresses and maximum shear stress

Mohr's circle is a graphical method to find principal stresses, maximum shear stress, and stress transformation on any inclined plane at a point in a stressed body.

What is the Carnot efficiency of a heat engine operating between 600K and 300K?

Answer: 50%

Carnot efficiency = 1 - T_cold/T_hot = 1 - 300/600 = 0.5 = 50%. This is the maximum theoretical efficiency for any heat engine operating between these temperatures.

Poisson's ratio relates:

Answer: Lateral strain to axial strain

Poisson's ratio (ν) = -(lateral strain)/(axial strain). For most metals, ν ≈ 0.3. It indicates how much a material contracts laterally when stretched axially.

The specific heat capacity at constant pressure (Cp) is always greater than at constant volume (Cv) because:

Answer: At constant pressure, additional energy is needed for expansion work

At constant pressure, the system must do PdV expansion work in addition to increasing internal energy, requiring more heat input per degree of temperature rise. Cp - Cv = R for ideal gases.