Statics Flashcards

A 500 N force acts at a point 2 m from the pivot of a lever. What is the moment about the pivot?

Answer: 1000 N·m

Moment = Force × perpendicular distance = 500 N × 2 m = 1000 N·m.

Which condition must be satisfied for a body to be in static equilibrium?

Answer: Both ΣF = 0 and ΣM = 0

Static equilibrium requires both the sum of all forces and the sum of all moments to equal zero.

A truss joint has forces of 8 kN in member AB and 6 kN in member AC, oriented perpendicularly. What is the resultant force magnitude?

Answer: 10 kN

Resultant = √(8² + 6²) = √(64 + 36) = √100 = 10 kN by the Pythagorean theorem.

A uniform beam of weight 200 N and length 4 m is simply supported at both ends. What is the reaction force at each support?

Answer: 100 N

By symmetry and ΣFy = 0, each support carries half the beam weight: 200/2 = 100 N.

What is the unit vector in the direction of vector F = 3i + 4j?

Answer: 0.6i + 0.8j

Magnitude = √(9+16) = 5; unit vector = (3/5)i + (4/5)j = 0.6i + 0.8j.

In the method of sections for truss analysis, the maximum number of unknown member forces solvable with three equilibrium equations is:

Answer: 3

Three independent equilibrium equations (ΣFx, ΣFy, ΣM) allow solving for a maximum of 3 unknown forces.

A 10 kN load is applied at the midpoint of a simply supported beam of span 6 m. What is the maximum bending moment?

Answer: 15 kN·m

M_max = PL/4 = 10 × 6 / 4 = 15 kN·m for a midspan point load on a simply supported beam.