* Newton's First Law of Motion: An object at rest stays at rest, and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

* Constant Velocity: Since the rocket is moving with a constant velocity, its acceleration is zero (acceleration is the rate of change of velocity).

* Newton's Second Law of Motion: Force is equal to mass times acceleration (F = ma). If acceleration is zero, then the force must also be zero.

In other words, if there's no change in the rocket's motion, there's no net force acting on it.