Calculate Rate of Disintegration of Projectile

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Discussion Overview

The discussion revolves around the calculation of the rate of disintegration of a projectile, specifically focusing on meteoroids entering the atmosphere. Participants explore various factors influencing disintegration, including material properties, velocity, and interactions with air at hypervelocity. The scope includes theoretical considerations and exploratory reasoning rather than definitive calculations or outcomes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant outlines a general thought process for calculating disintegration, proposing a hypothetical scenario involving a sphere of iron at high velocity.
  • Another participant emphasizes the complexity of the problem, suggesting that simple formulas may not adequately capture the interactions at hypervelocity.
  • Some participants express interest in understanding the journey of the calculation, focusing on the factors that influence disintegration rather than seeking a final answer.
  • There is a suggestion to assume that the kinetic energy of the projectile is converted into heat, which could provide a basis for understanding energy release.
  • Participants discuss various potential fates of the material, including combustion, evaporation, thermal cracking, and explosion, highlighting the importance of rate of heating and thermal conductivity.
  • Questions are raised about how to determine the heat gained from air friction and the transfer of heat into the center of the sphere, indicating a need for further exploration of thermal conductivity's role in disintegration.

Areas of Agreement / Disagreement

Participants generally agree on the complexity of the problem and the need for a nuanced approach, but multiple competing views remain regarding the specific factors and methodologies to consider in the calculations.

Contextual Notes

Limitations include assumptions about the projectile's behavior, such as ignoring gravity and the potential for macroscopic fragmentation, which may affect the analysis. The discussion also reflects uncertainty regarding the influence of various physical properties on disintegration.

Skyler0114
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I was thinking about meteorioids and how upon their entry into the atmosphere the large amount of disintegration they experience so i wanted to try running through a calculation of something similar to see if i could i understand it better. I'm going to outline a general thought process I've come up with then ask a specific case.
Ignoring gravity or the existence of a floor for now because of the complications that would cause.

General:
Lets say we have a [insert size and mass/density here] [insert shape name here] of [insert material here] [falls apart/does not fall apart] and we fire it at [insert velocity here].
Question:
How [long or far] will it travel before the object fully disintegrates?
OR
How [much mass/volume] is lost before the object stops disintegrating.

Example:
Lets say we have a 1 meter radius sphere of iron (density 7.874 g·cm−3) in 1 atm air. We assume it does not fall apart or explode in it's transit. We fire it at 100 km/s, how much mass does the object lose in its transit.
 
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Not a simple problem. The interactions between the projectile and the air as it is traveling at hypervelocity do not lend themselves, IMO, to analysis by a couple of simple formulas.
 
SteamKing said:
Not a simple problem. The interactions between the projectile and the air as it is traveling at hypervelocity do not lend themselves, IMO, to analysis by a couple of simple formulas.

Im not really interested in a simple formula as much as trying to piece together information to come up with more information and more formulas. I'm interested in the journey for this calculation, not so much the end product.

As more variables are introduced I want to see what you have to consider and what doesn't matter.
 
Skyler0114 said:
Im not really interested in a simple formula as much as trying to piece together information to come up with more information and more formulas. I'm interested in the journey for this calculation, not so much the end product.

As more variables are introduced I want to see what you have to consider and what doesn't matter.

If you're thinking about meteorites hitting the earth...
You could start by assuming that the entire kinetic energy of the projectile is converted into heat. That's a pretty good approximation for the total energy released.
 
Nugatory said:
If you're thinking about meteorites hitting the earth...
You could start by assuming that the entire kinetic energy of the projectile is converted into heat. That's a pretty good approximation for the total energy released.

I was more interested in learning about the rate of disintegration, distances traveled, heats experienced, and just about different factors that need to be considered and how each of them would likely be playing out as per the relevant formulas .
 
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What fates may befall the material? Combustion, evaporation, thermal cracking, explosion... Rate of heating will matter, since rapid external heating would create greater stresses. Conductivity. Spin?
 
haruspex said:
What fates may befall the material? Combustion, evaporation, thermal cracking, explosion... Rate of heating will matter, since rapid external heating would create greater stresses. Conductivity. Spin?

For now let's assume the particle does not fracture into macroscopic fragments. Should a fate like that befall it then instead the methodology we create here can instead be reapplied for the fragments in question (with a lot of new variables that is).

How would one be able to determine the heat gained from air friction?

Also how would one be able to determine the transfer of heat into the "cooler" center of the sphere?

Obviously thermal conductivity comes to play a very large role here but even if the conductivity high is would it effect disintegration in the first (maybe few) second(s) at some non-negligible amount?
 
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