Equilibrium & Lami's Theorem

ΣF = 0; Lami for concurrent forces.

Concept

Equilibrium & Lami's Theorem is a foundational idea in this chapter. The defining relationship is:

$F_1/\sin\alpha = F_2/\sin\beta = F_3/\sin\gamma$

Lami applies to three concurrent forces in equilibrium.

Worked Application

Apply the formula to a typical problem from your textbook. Identify the knowns, plug into the equation, and check that the units work out. Always sanity-check the magnitude before accepting an answer.

Common Confusions

• Confusing the variables in the formula — re-read the symbol definitions in the chapter.
• Forgetting unit conversions (cm vs m, g vs kg).
• Ignoring sign conventions where direction matters.

Key Takeaways

• Master the formula $F_1/\sin\alpha = F_2/\sin\beta = F_3/\sin\gamma$ and one canonical example.
• See the chapter index for full derivations, traps and exam-grade problems.