SCE Engineering Sciences 4

Question 1

What is the principle of virtual work?

Accepted Answer

A system in equilibrium does zero virtual work for any virtual displacement

Answer

The principle states that for a system in static equilibrium, the total virtual work done by all forces during any compatible virtual displacement is zero. It is powerful for solving indeterminate structures.

Question 2

Fourier's law of heat conduction states that heat flux is proportional to:

Accepted Answer

The negative temperature gradient

Answer

Fourier's law: q = -k(dT/dx), where the negative sign indicates heat flows from high to low temperature. The thermal conductivity k depends on the material.

Question 3

The natural frequency of a single degree of freedom system is:

Accepted Answer

ωn = √(k/m)

Answer

The natural frequency ωn = √(k/m) where k is stiffness and m is mass. This determines the frequency at which the system oscillates freely and is critical for avoiding resonance.

Question 4

In materials science, what is creep?

Accepted Answer

Time-dependent deformation under constant stress at elevated temperature

Answer

Creep is the slow, progressive plastic deformation of a material under constant stress over time, especially at temperatures above ~0.4 of the melting point. This is particularly relevant in Saudi Arabia's hot climate.

Question 5

The drag coefficient of a sphere in laminar flow is given by Stokes' law as:

Accepted Answer

CD = 24/Re

Answer

For very low Reynolds numbers (Re < 1), Stokes' law gives CD = 24/Re for a sphere. This applies to slow-moving particles, sediment settling, and dust particle analysis.

SCE Engineering Practice Test

SCE Engineering Practice Test

SCE Engineering Sciences 4