MomentumCopy

Cheat Sheet: Momentum & Impulse (O Level / IGCSE Physics)

1. Momentum

• Definition:
  Momentum is the product of mass and velocity
• Equation:
  p = m × v
  where:
  p = momentum (kg·m/s)
  m = mass (kg)
  v = velocity (m/s)
• Vector quantity: Direction matters (same as velocity)

2. Impulse

• Definition:
  Impulse is the product of force and the time for which the force acts.
  It also equals the change in momentum.
• Equation:
  Impulse = F × ∆t = ∆(mv)
  where:
  F = force (N)
  ∆t = time (s)
  ∆(mv) = change in momentum (kg·m/s)
• Impulse causes momentum to change — e.g., in collisions or sudden stops

3. Conservation of Momentum

• Principle:
  In a closed system with no external forces,
  Total momentum before = Total momentum after
• One-Dimensional Problems:
  m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
  where:
  m = mass
  u = initial velocity
  v = final velocity
• Use signs to indicate direction (right = +, left = −)

4. Resultant Force and Momentum

• Definition:
  Resultant force is the rate of change of momentum
• Equation:
  F = ∆p / ∆t
  = (mv − mu) / ∆t
  where:
  F = resultant force (N)
  ∆p = change in momentum (kg·m/s)
  ∆t = time taken (s)
• Links Newton’s Second Law to momentum changes