Final answer:
The net force on a rocket is calculated by adding the thrust or upward force and subtracting the weight or downward force as well as any other forces acting on the rocket. This force ultimately determines the rocket's motion.
Step-by-step explanation:
The blank space in your sentence is where the term net force would be inserted. In the context of physics, the net force on a rocket includes the rocket's thrust or upward force, minus its weight, which is the downward force acting upon it. Additionally, it would include all other forces that are exerted on the rocket. A rocket's motion is determined by these combined forces.
For example, if a rocket is launching, the thrust created by expelling the fuel downward creates an upward force. This is counteracted by the force of gravity pulling the rocket downward. There may be other forces too, like air resistance. When we subtract the weight of the rocket and all these forces from the thrust, we get the net force that really moves the rocket.
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