Terminal velocity and momentum

• • Newton's third: for every action there is an equal and opposite reaction.
• Conservation of Momentum

  In a closed system, the total momentum before an event is equal to the total momentum after the event.

  This conservation of momentum is most often referred to during collisions, but also applies to rockets and projectiles.

  With rockets, the momentum gained by the exhaust being expelled backwards is equal to the momentum gained by the rocket moving forwards.

  With projectiles, the recoil momentum of the gun is equal to the momentum of the bullet.