Fundamentals of Engineering FE Knowledge 5

Question 1

Which failure theory is most appropriate for ductile materials under static loading?

Accepted Answer

Maximum shear stress (Tresca) theory

Answer

The Tresca (maximum shear stress) criterion is commonly used and conservative for ductile materials under static loads.

Question 2

For a second-order linear ODE with characteristic roots r = −2 ± 3i, the general solution is:

Accepted Answer

e^(-2t)(C₁cos3t + C₂sin3t)

Answer

Complex roots α ± βi give the solution e^(αt)(C₁cosβt + C₂sinβt); here α = −2, β = 3.

Question 3

In Mohr's Circle for plane stress, the radius of the circle represents:

Accepted Answer

The maximum in-plane shear stress

Answer

The radius of Mohr's Circle equals the maximum in-plane shear stress τ_max.

Question 4

Darcy-Weisbach equation is used to calculate:

Accepted Answer

Head loss due to friction in a pipe

Answer

The Darcy-Weisbach equation h_f = f(L/D)(V²/2g) computes frictional head loss in a pipe.

Question 5

A capacitor of 100 μF is charged to 50 V. How much energy is stored?

Accepted Answer

0.125 J

Answer

Energy W = ½CV² = ½ × 100×10⁻⁶ × 50² = ½ × 100×10⁻⁶ × 2500 = 0.125 J.

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