Rocket engines lift a rocket from the earth surface because hot gas with high velocity

Options

A. Push against the earth
B. Push against the air
C. React against the rocket and push it up
D. Heat up the air which lifts the rocket

Answer

To solve the question regarding how rocket engines lift a rocket from the Earth's surface, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding the Principle**: The operation of a rocket engine is primarily governed by Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. This principle is fundamental to how rockets generate thrust.

2. **Combustion Process**: In a rocket engine, fuel is burned (combusted) to produce hot gases. This combustion occurs in the combustion chamber of the rocket engine.

3. **Gas Expulsion**: The hot gases produced during combustion are expelled at high velocity out of the rocket's nozzle. This expulsion of gas is the action force.

4. **Reaction Force**: According to Newton's Third Law, the expulsion of gas downwards generates an equal and opposite reaction force that pushes the rocket upwards. This upward force is known as thrust.

5. **Thrust vs. Weight**: For the rocket to lift off, the thrust generated by the engine must be greater than the weight of the rocket (the force due to gravity acting on it). When the thrust exceeds the weight, the rocket accelerates upwards.

6. **Effect on Surrounding Air**: As the rocket ascends, the hot gases also push against the surrounding air, contributing to the overall lift. However, the primary lifting force is due to the reaction of the gases being expelled downwards.

7. **Conclusion**: Therefore, the rocket lifts off the Earth's surface primarily because the hot gases are expelled at high velocity, creating a thrust that overcomes the weight of the rocket.

### Final Answer:
The rocket engine lifts a rocket from the Earth's surface because the hot gas with high velocity pushes against the rocket, creating thrust that is greater than the weight of the rocket.

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