4.1.3—Forces
- Syllabus
- 9709–2028–2029
- Objective
- 4.1.3
- Level
- AS
Equilibrium requires the resultant force to vanish in every independent direction
A particle is in equilibrium when ΣF=0. Resolve horizontally and vertically (or along chosen axes), giving one scalar equation per independent direction.
Include all external forces, use geometry to express angles, and solve the component equations together. A zero horizontal resultant alone does not ensure equilibrium.
A weight supported by two symmetric strings has equal tensions; horizontal components cancel and vertical components sum to the weight.
Equilibrium does not mean no forces act; it means their vector sum is zero.
ConceptA-Level CAIE Mathematics AS