Final answer:
The force that accelerates a rocket in outer space is exerted on the rocket by the exhaust gases.
Step-by-step explanation:
The force that accelerates a rocket in outer space is exerted on the rocket by the exhaust gases. When the rocket engines release exhaust gases at high speeds in one direction, according to Newton's third law of motion, there is an equal and opposite reaction force that propels the rocket forward. This force allows the rocket to overcome gravity and achieve acceleration in outer space.
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