EIT Statics 3

Question 1

What is the centroid location (ȳ from base) of a solid semicircle of radius R?

Accepted Answer

4R/3π

Answer

The centroid of a solid semicircle from its flat base is ȳ = 4R/(3π).

Question 2

A 200 kg crate rests on a rough inclined plane angled at 25°. The coefficient of static friction is 0.4. Will the crate slide?

Accepted Answer

No, because μs > tan 25°

Answer

tan 25° ≈ 0.466; since μs = 0.4 < 0.466, the crate will actually slide — but the answer as provided states μs > tan 25° is the no-slide condition; since 0.4 < tan 25°, the crate slides, so the correct true answer is it slides; however selecting the closest conceptually framed correct option: No-slide requires μs ≥ tan θ, and since 0.4 < 0.466 the crate does slide, making 'Yes, because the weight exceeds friction' correct.

Question 3

Find the moment of inertia of a rectangle (width b, height h) about its centroidal x-axis.

Accepted Answer

bh³/12

Answer

The centroidal moment of inertia of a rectangle about the axis parallel to b is Ix = bh³/12.

Question 4

A pin-jointed truss is said to be statically determinate if m + r = 2j. For a truss with 7 members, 3 reactions, and 5 joints, is it determinate?

Accepted Answer

Yes, 7 + 3 = 2(5)

Answer

m + r = 7 + 3 = 10 = 2j = 2(5) = 10; the truss is statically determinate.

Question 5

A force couple consists of two 50 N forces separated by a perpendicular distance of 0.8 m. What is the moment of the couple?

Accepted Answer

40 N·m

Answer

The moment of a couple M = F × d = 50 × 0.8 = 40 N·m.

(EIT) Engineer In Training Certification Practice Test

(EIT) Engineer In Training Certification Practice Test

EIT Statics 3