A rocket can go vertically upward in Earth's atmosphere because:
Correct answer: D. Of the force exerted on the rocket by gases ejected by it
- A. It is lighter than air
- B. Of gravitational pull of Earth
- C. It has a fan, which displaces more air per unit time then, the weight of rocket
- D. Of the force exerted on the rocket by gases ejected by it
Explanation
D is the correct answer. Rockets work on the principle of action and reaction (Newton's third law of motion). As the rocket expels gases at high speed through its rocket nozzles, the expelled gases exert a force (thrust) on the rocket in the opposite direction. This thrust is greater than the weight of the rocket, allowing it to lift off and move upward.
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Newton’s law of universal gravitation relates the force between masses to their masses and separation, while gravitational field strength explains weight and orbital motion. The topic covers satellite velocity and period, escape ideas, weightlessness in free fall, and artificial gravity, which differs from ordinary gravitational attraction.
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