Statics Flashcards

A 600 N box rests on a surface with a coefficient of static friction μs = 0.35. What is the maximum friction force before sliding begins?

Answer: 210 N

F_max = μs × N = 0.35 × 600 = 210 N.

At an unloaded joint where only two non-collinear members meet, those members carry:

Answer: Zero force

By equilibrium at an unloaded joint with two non-collinear members, both must be zero-force members.

The centroid of a triangle is located at what fraction of the height measured from the base?

Answer: 1/3

The centroid of a triangle is located at h/3 from the base, or one-third of the total height.

A force F = 50 N acts at an angle of 30° above the horizontal. What is the horizontal component Fx?

Answer: 43.3 N

Fx = F cos(30°) = 50 × 0.866 = 43.3 N.

Varignon's theorem states that the moment of a resultant force about a point equals:

Answer: The sum of the moments of its components about that point

Varignon's theorem states M_R = ΣM_components, allowing force components to replace the resultant.

A concurrent force system has F1 = 10i + 5j kN and F2 = −4i + 8j kN. What is the resultant?

Answer: 6i + 13j kN

R = (10−4)i + (5+8)j = 6i + 13j kN by vector addition.

What is the moment of inertia of a rectangle (width b, height h) about its centroidal axis parallel to b?

Answer: bh³/12

The centroidal moment of inertia of a rectangle about its horizontal axis is I = bh³/12.