Science

Conservation of momentum.

Definition

The law of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act on it. This principle is especially useful in analyzing collisions and explosions.

Examples

Real-world.

  • 1 When a gun fires, the bullet moves forward and the gun recoils backward with equal and opposite momentum
  • 2 In ice skating, when two skaters push off each other, they move apart with momenta that are equal in magnitude but opposite in direction
  • 3 Rocket propulsion works because the momentum of exhaust gases ejected backward equals the forward momentum gained by the rocket
Key Fact

p_total = m₁v₁ + m₂v₂ = constant (when net external force = 0).