Here are the essential concepts you must grasp in order to answer the question correctly.
Thrust
Thrust is the force exerted by a rocket or engine to propel it forward. It is generated by expelling mass (in this case, fuel) at high velocity. According to Newton's third law, for every action, there is an equal and opposite reaction; thus, the thrust produced is equal to the rate of change of momentum of the expelled gas.
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Momentum
Momentum is the product of an object's mass and its velocity, representing the quantity of motion it possesses. In the context of rockets, the momentum change of the expelled fuel contributes to the thrust. The formula for momentum is p = mv, where p is momentum, m is mass, and v is velocity.
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Conservation of Momentum
The conservation of momentum principle states that in a closed system, the total momentum remains constant if no external forces act on it. For rockets, as fuel is burned and expelled, the momentum of the rocket and the expelled gas must balance, allowing the rocket to gain forward momentum while the gas moves in the opposite direction.
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