EIT Statics, Dynamics & Mechanics of Materials 4

Question 1

A projectile is launched at 45° with an initial speed of 20 m/s. Neglecting air resistance, what is the maximum height? (g = 9.81 m/s²)

Accepted Answer

10.2 m

Answer

H = (v₀sin45°)²/(2g) = (20×0.707)²/(19.62) = 200×0.5/19.62 ≈ 10.2 m.

Question 2

Shear stress in a circular shaft under torque T is maximum at the:

Accepted Answer

Outer surface

Answer

Torsional shear stress τ = Tc/J is maximum at the outermost fiber where c is maximum.

Question 3

The principle of transmissibility states that a force on a rigid body can be moved along its:

Accepted Answer

Line of action without changing equilibrium

Answer

Transmissibility: a force may be applied at any point along its line of action and produce the same external effect on a rigid body.

Question 4

Euler's buckling load for a pin-pin column of length L, modulus E, and moment of inertia I is:

Accepted Answer

π²EI/L²

Answer

Euler's critical load Pcr = π²EI/L² for a pin-pin column (K=1), the fundamental column buckling formula.

Question 5

A material has E = 200 GPa and ν = 0.3. What is its shear modulus G?

Accepted Answer

76.9 GPa

Answer

G = E/[2(1+ν)] = 200/[2(1.3)] = 200/2.6 ≈ 76.9 GPa.

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