Engineering Sciences Flashcards

What is the Gibbs phase rule?

Answer: F = C - P + 2, relating degrees of freedom, components, and phases

Gibbs phase rule F = C - P + 2 determines the number of independent intensive variables (degrees of freedom F) for a system with C components and P phases in equilibrium.

The Castigliano's second theorem states that the displacement at a point equals:

Answer: The partial derivative of strain energy with respect to the force at that point

Castigliano's theorem: δᵢ = ∂U/∂Fᵢ, where U is the total strain energy and Fᵢ is the force at point i. This is powerful for calculating deflections in complex structures.

In electrical engineering, Ohm's law states:

Answer: V = IR (voltage equals current times resistance)

Ohm's law V = IR is fundamental to circuit analysis, stating that voltage across a conductor is directly proportional to the current flowing through it, with resistance as the proportionality constant.

What is the principle of superposition applicable to?

Answer: Linear systems only

Superposition applies only to linear systems where the response to combined inputs equals the sum of individual responses. It is widely used in structural analysis and circuit theory within the linear range.

The thermal conductivity of most metals is related to their electrical conductivity through:

Answer: The Wiedemann-Franz law

The Wiedemann-Franz law states that the ratio of thermal to electrical conductivity is proportional to temperature (k/σ = LT, where L is the Lorenz number), because free electrons carry both heat and charge.

What is the difference between isotropic and anisotropic materials?

Answer: Isotropic materials have the same properties in all directions; anisotropic do not

Isotropic materials (most metals) have uniform properties in all directions, while anisotropic materials (wood, composites, crystals) have direction-dependent properties, requiring more complex analysis.