If three coplanar forces maintain static equilibrium on a rigid body, what geometric condition must they satisfy___________________?
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Answer: D. all the above are correct
Explanation
Three coplanar forces in static equilibrium must be either all parallel or concurrent. Concurrency at a single point ensures that the resultant moment about that point equals zero. Parallel force systems achieve equilibrium through proper spacing and opposing force magnitudes. Static equilibrium requires both the resultant force vector and resultant moment to equal zero. Lami theorem applies specifically to three concurrent coplanar forces in static balance. Geometric compatibility conditions must be satisfied for rigid bodies under coplanar loading.
Civil engineers apply equilibrium equations to analyze truss joints and structural frame supports. Verifying force concurrency prevents structural collapse in complex building frameworks. Statics problem solving relies on these geometric rules for coplanar force systems. Saying they only meet in a point ignores the valid equilibrium case where forces are parallel. Stating they are all parallel ignores the equally valid concurrent force intersection case. Saying at least two meet is incomplete because three non-parallel forces must all intersect.
- Subject
- Engineering
- Category
- Mechanical Engineering
- Topic
- —
- Difficulty
- medium
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