Action and reaction of a rocket in space.

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Discussion Overview

The discussion revolves around the mechanics of rocket propulsion in space, specifically focusing on the principles of momentum conservation and Newton's third law of motion. Participants explore how the ejection of gas propels the rocket and the forces involved in this process.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • Some participants assert that a rocket can be propelled forward by ejecting mass, such as gas, based on the conservation of momentum.
  • There is a question regarding what the force acts on when gas is ejected, with one participant suggesting it acts on the rocket itself.
  • Another participant emphasizes that the propelling force can be explained through Newton's third law, highlighting the action and reaction involved in the process.
  • A further inquiry is made about the forces acting on the gas during ejection, questioning the source of the force that directs the gas in a specific direction rather than allowing it to expand uniformly.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the specifics of the forces involved in rocket propulsion, and multiple viewpoints are presented without a clear consensus on the explanations provided.

Contextual Notes

The discussion does not resolve the assumptions about the forces acting on the gas or the mechanics of the combustion process within the rocket engine.

Clara Chung
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By conversation of momentum, the rocket can be propelled forward by ejecting mass like gas.
However, how is the propelling force explained in terms of action and reaction? If gas is ejected, what does the force act on?
 
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Clara Chung said:
If gas is ejected, what does the force act on?
The rocket.
 
Clara Chung said:
By conversation of momentum, the rocket can be propelled forward by ejecting mass like gas. However, how is the propelling force explained in terms of action and reaction?
Conversation of momentum is ensured by Newton's 3rd Law (action and reaction).
 
Clara Chung said:
If gas is ejected, what does the force act on?

Russ already answered this, but think for a moment. What's acting on the gas to eject it? Where's that force coming from? If the combustion process inside the engine creates a high speed gas, what forces it to go one way instead of expanding outwards in all directions?
 

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