Will gravity affect the splash of a pebble in the underground lake on Mars?

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Discussion Overview

The discussion revolves around the effects of Martian gravity on the behavior of a pebble when skipped across an underground lake on Mars. Participants explore the implications of lower gravity on the distance and height of splashes compared to Earth, considering both theoretical and practical aspects.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants suggest that the lower gravity on Mars would allow a pebble to travel farther when skipped compared to Earth.
  • There is uncertainty regarding how the number of skips would be affected by gravity, with some proposing that it may not depend on gravity if other factors remain constant.
  • One participant raises the possibility that in very low gravity, surface tension could dominate the interaction, potentially resulting in little to no splash when a pebble hits the water.
  • Concerns are mentioned about practical limitations, such as wearing a spacesuit, which could affect throwing ability and complicate the act of skipping a pebble.

Areas of Agreement / Disagreement

Participants generally agree that the distance a pebble travels would be greater on Mars due to lower gravity, but there is no consensus on how gravity affects the mean number of skips or the height of the splash. The discussion remains unresolved regarding these aspects.

Contextual Notes

Participants acknowledge the complexities introduced by the underground location of the lake and the potential influence of surface tension in low gravity environments, which remain unresolved in the discussion.

Yoni
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They found an underground lake on Mars last week!
Given that the lake exists and is actually liquid (and has a surface), two obvious questions come to mind:
1. Will I be able to beet my earthly current record in bouncing a pebble there?
2. If I release a pebble from a given height here and there, which splash will be higher?

Cheers to space exploration!
 
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Yoni said:
They found an underground lake on Mars last week!
Given that the lake exists and is actually liquid (and has a surface), two obvious questions come to mind:
1. Will I be able to beet my earthly current record in bouncing a pebble there?
Do you mean "skipping" a pebble? What record do you mean here -- number of skips or distance travelled?
The gravity on Mars is only 38% of the gravity here on Earth (http://coolcosmos.ipac.caltech.edu/ask/73-How-strong-is-the-gravity-on-Mars-), so a rock would travel farther after each skip. As far as the number of skips, I don't know how the lower gravity would affect this.

As on Earth, you would not want to use a pebble, but would want to choose a rock with a flat surface. As English is probably not your first language, a pebble is a small stone, typically roundish. A good skipping stone would tend to be larger than a pebble.
Yoni said:
2. If I release a pebble from a given height here and there, which splash will be higher?
Seems pretty obvious to me that with lower gravity on Mars, the splash from a pebble would be higher there.
 
Yoni said:
Will I be able to beet my earthly current record in bouncing a pebble there?
I assume you mean "beat" and "skip", not "beet" and "bounce". Given that Mars has about 1/3 the gravity of Earth, I don't see how you could not beat the record but there are some complications. You'd have to be wearing a spacesuit so your throwing ability would be limited. THEN of course, there is the real killer which is that it is about a mile underground which is REALLY going to complicate rock skipping :smile:
 
I did mean "beat" and "skip", and I guess our pebbles here are flatter than yours... :)
In any case, while it is trivial that the distance would be longer, My first guess was that the mean number of skips would not depend on gravity (if all other factors are similar).
Regarding the height of a splash: Let's take it to the extreme. In very low gravity, surface tension completely governs the process. The rock would meet the water with very low velocity and the surface tension would pull it into the water, and I would presume make no splash at all.
 
Yoni said:
My first guess was that the mean number of skips would not depend on gravity (if all other factors are similar).
That's a good point. I had not looked at it that way, I was just thinking of the distance.
 

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