Which Travels Fastest: Sea Wave, Mercury Wave, or Moon Wave?

  • Context: High School 
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Discussion Overview

The discussion centers around the comparative speeds of surface waves on three different mediums: sea water, liquid mercury, and liquid mercury on the moon. Participants explore the factors that may influence wave speed, including density and gravity, while considering theoretical and intuitive approaches.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Some participants suggest that denser liquids and higher gravity may increase a wave's speed, proposing that a wave on liquid mercury would be the fastest.
  • Another participant presents a formula for surface-wave velocity, indicating that wave speed is proportional to the square root of gravity times the depth of the liquid, supporting the idea that mercury would yield the fastest wave.
  • Contrarily, one participant argues that less dense liquids may allow for faster wave propagation, using the analogy of a light foam compared to mercury, suggesting that water may actually be the fastest medium.
  • Another participant uses an intuitive approach to argue that the energy dynamics in lighter versus heavier liquids could influence wave speed, implying that the conditions of gravity could also play a role in determining which medium allows for the fastest wave.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between density, gravity, and wave speed, with no consensus reached on which medium allows for the fastest wave. Multiple competing perspectives remain unresolved.

Contextual Notes

Participants rely on intuitive reasoning and rough approximations, with some mathematical considerations mentioned but not fully explored. The discussion does not resolve the assumptions regarding the effects of gravity and density on wave speed.

Crumbles
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[a] a wave on the surface of the sea?
a wave on the surface of liquid mercury (dense metal)?
[c] a wave on the surface of liquid mercury on the moon?
 
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I think that denser liquids, and higher gravity both increase a wave's speed (but I'm only guessing). If I'm right, then would be the fastest.
 
As far as i remember, the rough approximation to the surface-wave-velocity is v~sqrt(g*h), where h is the depth of the "lake".
now, imho "the denser the liquid - the greater the speed" is conserved for surface waves, so is the answer we are looking for...
 
I think for surface waves it is the other way around - less dense=faster. Imagine if the ocean was a light foam. Any sort of surface wave you make would travel very fast. Now, if you imagine a pool of mercury it would be much slower because it has more intertia.

So I think the answer is A) water. But I didn't try to use any math so I could be way off because intuition can be misleading...
 
Using the intuitive approch imagine the first wave being started from within a box where we insantly remove the bottom and one side.

The light foam like water would have much less potential energy stored to convert into kinentic energy. Being less forceful and moving more slowly on the other light foam like water. While the heavy would move more energy in a smaller wave would likly move faster. Same reasoning for taking B over C for the more force in high G.

(Now watch it turn out to be the same for all!)
 

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