Force Equilibrium

For two known forces P, Q at an angle, compute the resultant magnitude, direction and the equilibrant (equal & opposite) force.

Inputs

Formula

R = √(P² + Q² + 2PQ cosα); Equilibrant Feq = R (opposite)
F₁F₂F₃三力共点平衡 (拉密定理)
Force Equilibrium schematic

How to use

  1. Fill in Force P, Force Q, Angle α in the Inputs section (watch the unit on each field).
  2. Click Calculate; the tool evaluates the formula shown above.
  3. Read Resultant R, Resultant dir. θ, Equilibrant Feq in the results area.
Formula notesThree-force equilibrium (Lami): F₁/sinα₁ = F₂/sinα₂ = F₃/sinα₃, α = opposite angles.