Grade 12 · Theory
Conservation of momentum
Momentum and impulse · about 3 min
Total momentum before equals total momentum after.In an isolated system, total momentum before a collision equals total momentum after.
Key points- Total p before = total p after, when no external net force acts.
- Applies to collisions and explosions alike.
- Write the equation with signs: m₁v₁ᵢ + m₂v₂ᵢ = m₁v₁f + m₂v₂f.
- Objects that stick together share a common final velocity.
- Isolated system — no external net force acts.
EXAM TIP
state "the system is isolated so momentum is conserved" before the calculation — it is a marked justification.