- #31
Antiphon
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It can be. It's just not very efficient propulsion.
Maybe a flashlight is like a roman candle.
Maybe a flashlight is like a roman candle.
Refrigerators are like rockets, right?
- Context: Undergrad
- Thread starter Dreslan
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- Refrigerators Rockets
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Discussion Overview
The discussion revolves around the mechanics of refrigerators and their heat dissipation, drawing analogies to rockets. Participants explore concepts of momentum, energy transfer, and the implications of heat as molecular motion, questioning why refrigerators do not recoil despite losing momentum through heat expulsion.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- Some participants suggest that the heat expelled from a refrigerator represents molecular motion with energy and momentum, questioning why the refrigerator does not recoil.
- Others propose that the momentum lost is negligible compared to the forces holding the refrigerator in place, such as friction and gravity.
- A participant raises a related question about the ballistic pendulum, discussing the conservation of momentum and the potential impact of heat loss on measurements.
- Some argue that the random nature of kinetic energy in hot objects means there is no net recoil force, while others challenge this view by emphasizing the directional aspects of heat loss from the radiator.
- A later reply questions the assumption that momentum lost in various directions balances out, suggesting that there could be a net forward force on the refrigerator.
- Participants discuss the implications of the refrigerator's design and the placement of its radiator on the direction of heat loss and potential movement.
Areas of Agreement / Disagreement
Participants express differing views on the implications of heat loss and momentum transfer, with no consensus reached on whether the refrigerator experiences any significant recoil or movement due to expelled heat.
Contextual Notes
Some discussions involve assumptions about the negligible effects of heat loss and the role of external forces, which remain unresolved. The complexity of momentum transfer in the context of heat dissipation is also noted but not fully explored.
- #32
russ_watters
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It can be - it just doesn't provide very much (as I discussed earlier).brainstorm said:
- #33
brainstorm
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Antiphon said:
Maybe a roman candle is like a sparkler scaring away fireflies. These absurd analogies are fun. I think a whole section of the forum should be devoted to them. It would be like youtube without the videos.
- #34
DaveC426913
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It is. In principle.Antiphon said:
- #35
brainstorm
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DaveC426913 said:
Why, because they both send out discrete packages of luminosity that require chemical propellant to achieve subsonic velocity and then fade away after @50ft?
Or because they're both cylindrical and produce illumination?
- #36
DaveC426913
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brainstorm said:
Because both produce thrust.
- #37
brainstorm
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DaveC426913 said:
Ok, let's assume you were trying to come up with a propulsion system that uses EM radiation. Obviously you want it as efficient as possible in terms of unit energy to unit propulsion. What would the variable parameters be for waste? Would there be certain wavelengths that would generate more thrust than others?
- #38
DaveC426913
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brainstorm said:
My post 34 consists of exactly 4 words. Of those 4 words, it seems I have the need to repeat two of them:
In principle.
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