Newton’s Laws
Newton’s Third Law
For every action there is an equal, but opposite, reaction.
This law states that if you exert a force on some object then that object will exert the same amount of force on you. You and the object form an action-reaction pair. For rockets the pair is the rocket and the gas expelled by the engines. The rocket exerts a force on the expelled gasses and the gas exert the same force on the rocket. Since the gasses are pushed away from the rocket, the rocket is propelled in the direction directly away from the gasses. If you look back at Newton's Second Law you will find that F=ma. Combined with the third law you will find that the force is the same but if the masses of the two objects are different then the accelerations will be different.