Which principle explains how rockets are propelled forward when fuel is ejected in the opposite direction?
Show answer & explanation
Correct answer: C
Explanation
Correct Answer
Newton’s Third Law of Motion
Explanation
Newton’s Third Law of Motion states that for every action, there is an equal and opposite reaction. In the case of a rocket, the engine burns fuel to create high-pressure gas, which is expelled backward at high velocity (the action). In response, the rocket experiences an equal and opposite force that pushes it forward (the reaction). This principle of action and reaction is what allows a rocket to move even in the vacuum of space, where there is no air to push against.
Key Points
The total momentum of the rocket and the ejected gas is conserved, which is also a manifestation of the Law of Conservation of Momentum. While the rocket pushes gas out, the gas pushes back on the rocket. This force, known as thrust, must exceed the force of gravity (in the early stages of launch) to enable the rocket to accelerate away from the Earth’s surface.
Important Questions and Answers
Question: What is the force that pushes a rocket forward called?
Answer: Thrust.
Question: Can a rocket propel itself in space where there is no atmosphere?
Answer: Yes, because it operates on the principle of momentum conservation and action-reaction, which does not require an external medium like air.