Difficulty: Easy
Correct Answer: All of these
Explanation:
Introduction / Context:Understanding how a general system of coplanar non-concurrent forces affects a rigid body is key to predicting motion or ensuring equilibrium in structures and mechanisms.
Given Data / Assumptions:
Concept / Approach:A general planar force system can be reduced to a single resultant force and a resultant moment (couple). Depending on whether the net force and/or net moment vanish, the body may translate and rotate (general plane motion), rotate without translation (pure couple), or remain at rest (complete equilibrium).
Step-by-Step Solution:
Compute ΣF_x, ΣF_y, and ΣM_O.If ΣF ≠ 0 and ΣM ≠ 0 → general plane motion (translation + rotation).If ΣF = 0 and ΣM ≠ 0 → pure rotation due to a couple.If ΣF = 0 and ΣM = 0 → complete equilibrium (no motion).Verification / Alternative check:Equivalent system reduction (force–couple) always exists in the plane; Chasles’ theorem supports decomposition into translation plus rotation.
Why Other Options Are Wrong:
Common Pitfalls:Assuming non-concurrent forces must always cause rotation; if arranged to cancel moments, pure translation can occur, but that requires special geometry.
Final Answer:All of these
Discussion & Comments