Effect of changing gravity on flying animals

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    Animals Flying Gravity
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Discussion Overview

The discussion centers on how changes in Earth's gravitational field could affect the ability of animals to fly. Participants explore various parameters such as weight, air density, air viscosity, climate change, and the evolution of flying creatures, as well as comparisons to sea creatures.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question how gravity changes would affect creature weight, air pressure, and density, suggesting that these factors are crucial for understanding flight dynamics.
  • One participant argues that changing gravity fundamentally alters the equations of motion, necessitating computer analysis for modeling scenarios.
  • Another participant notes that atmospheric pressure is proportional to gravity and the amount of gas in the atmosphere, implying that changes in gravity would affect air density and viscosity.
  • Some participants express skepticism about categorizing the topic as introductory physics, suggesting it is more complex and suitable for deeper discussion.
  • There are varying opinions on the effects of increased gravity, with some suggesting it could improve lift due to increased air density, while others argue that increased weight would degrade lift.
  • A participant raises the idea of exploring conditions for life on a hypothetical Earth-like planet with different gravity, questioning the interplay of various factors like atmosphere retention and chemical bonding.
  • One participant speculates that stronger gravity might lead to evolutionary pressures favoring lighter wing structures in flying creatures.

Areas of Agreement / Disagreement

Participants express differing views on the implications of changing gravity, with no consensus on the overall effects or the best way to model them. Some agree on the complexity of the topic, while others emphasize specific parameters that may influence flight.

Contextual Notes

Participants highlight the need for clarification on the scale of gravity change being discussed, whether it is a small percentage or a significant shift. There are also unresolved questions regarding the interactions of various factors affecting flight.

Loren Booda
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How would the ability to fly differ if the Earth's gravitational field were to change significantly?

Parameters of interest may include: weight, air density, air viscosity, climate change, evolution of flying creatures, comparison to sea creatures.
 
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Loren Booda said:
How would the ability to fly differ if the Earth's gravitational field were to change significantly?

Parameters of interest may include: weight, air density, air viscosity, climate change, evolution of flying creatures, comparison to sea creatures.
Start with creature weight air pressure and density. How would they change if gravity increased or decreased signficantly?

AM
 
Why don't you offer us your thoughts so far, and we'll help you out.
 
How would the ability to fly differ if the Earth's gravitational field were to change significantly?

This question seems trivial to me. You can change the magnitude of gravity, but that's about it. Our abilitiy to model motion in gravity is due mainly to the fact that it is a (on the macroscale) uniform field that points towards the center of the earth. If you change this inherent property of gravity, none of the equations of motion apply, and you would have to perform some type of computer analysis to model each senario.

Your paramaters of interest are not in relation to gravity.
 
Surely this context-rich open-ended scenario
isn't an introductory physics homework question!

Lift is obtained by momentum transfer rate to wing area.

We know that the atmospheric pressure is proportional to "g",
and proportional to the amount of gas (N molecules) in the atmosphere.
The amount of gas retained by Earth depends slightly on "g".
 
I was surprised (and disappointed) that my post was placed by the PF elite in "introductory" physics. I don't even know how to access that forum from the home page.

An increase in gravity should increase the absolute weight of objects, increase the density and viscosity of air. Think in terms of their effects on an airfoil.

Climate change, evolution of flying creatures, and comparison to sea creatures would be more long term subjects for speculation.
 
Yeah, I don't think this is HW either. Looks like a nice discussion topic.
 
I think you would have to specify on what scale the change is. Are we talking a percentage or orders of magnitude change?

It's going to be tricky to deduce what the overall effect would be. Looking at things independent from each other:

Increased gravity = increased air density (lift improves)
Increased gravity = increased weight of object (lift degrades)
Increased gravity = increased air pressure (lift improves)
Increased gravity = increased air temperature (lift degrades)
Increased gravity = increased air viscocity (? I am siding with lift improves but that really depends)
Increased gravity = increased humidity (lift degrades)

I'm not quite sure where it would all come out in the wash. Good question.
 
So say this was another Earth-like planet with an atmosphere of mix of oxygen and some other gas, and the mass of the planet was different, right? What is the n-dimensional formula for obtaining ideal conditions for life to be able to evolve on such a planet?

Lets say all variables were functions of gravity - atmosphere retention, chemical bounding, and an independent variable such as the type of available organic or otherwise matter (water, ammonia, acids, alkali, etc). Do we currently as humans have the capability to solve such question, drawing information from biology, physics, and chemistry?

I guess the next question and a more advanced one would be.. what is the range of possible evolutions such a creature may undergo?
 
  • #10
One might expect that a stronger gravity would increase the selection pressure towards light wings (porous bone structure, for example).

On Earth, a large glider bird like the albatross has extremely light wings relatively to wing length (the bone structure is very porous).
If the gravity becomes too strong, I'd assume large birds like the albatross will not be able to evolve.
 

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