Grade 11 · Theory
Forces in equilibrium
Vectors in two dimensions · about 3 min
Visual overview: Forces in equilibriumAn object in equilibrium has zero resultant force, so the components must cancel.
Key points- Equilibrium means Fnet = 0, so the object is at rest or moving at constant velocity.
- The sum of x-components is zero AND the sum of y-components is zero.
- Draw a free-body diagram showing every force acting ON the object.
- Three forces in equilibrium form a closed triangle.
- Equilibrium — zero resultant force.
- Free-body diagram — a sketch of all forces on one object.
EXAM TIP
label every force with its cause (weight, tension, normal) — unnamed arrows earn nothing.