Calculating Mass Lost of Iron Asteroid Hitting Earth

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Discussion Overview

The discussion revolves around calculating the mass lost by an iron asteroid as it enters Earth's atmosphere. Participants explore the factors influencing mass loss, including melting point, kinetic energy, drag force, and the mechanisms of ablation and fragmentation. The conversation includes both theoretical considerations and practical equations related to this scenario.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks an equation to calculate the mass lost of a spherical iron asteroid, emphasizing the importance of the melting point and kinetic energy.
  • Another participant questions the conversion of joules to Celsius, suggesting that it may not directly assist in answering the original question.
  • Some participants clarify that mass loss occurs primarily through ablation and fragmentation, and they reference an article for further reading.
  • A participant reiterates that it is not possible to convert degrees Celsius to joules directly, highlighting the distinction between temperature and heat.
  • One participant proposes that the usual model assumes all mass lost is vaporized, indicating the need for melting and vaporization points, specific heats, and latent heats to develop a comprehensive model.
  • It is noted that the energy for mass loss comes from the initial kinetic energy and gravitational potential energy lost during the fall, with atmospheric friction being the heating mechanism.

Areas of Agreement / Disagreement

Participants express differing views on the conversion of joules to Celsius and the implications for the original question. There is no consensus on a specific equation or model for calculating mass loss, and multiple competing perspectives on the factors involved remain present.

Contextual Notes

Limitations include the need for specific values for melting and vaporization points, specific heats, and latent heats, which are not provided. The discussion also reflects uncertainty regarding the proportion of energy that contributes to ablation.

dannyod6504
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I am trying to figure out an equation that will allow me to calculate the mass lost of an asteroid that is coming towards earth. I know what I need to know the melting point of the asteroid, in this case we are using a completely spherical iron asteroid. Also kinetic energy would most likely be a factor along with drag force. I just need to know how much mass is going to be lost after the asteroid enters the atmosphere.
 
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Possibly even a more a simple question that I would appreciate is if anyone knows how to convert joules to Celsius
 
Chronos said:
1 degree Celsius equals about 1899 Joules.

One Celsius heat unit is the quantity of heat required to raise the temperature of one pound of water by one degree Celsius. This is approximately equal to 1899 Joules.

It is not possible to convert degrees Celsius to Joules.
 
jbriggs444 said:
One Celsius heat unit is the quantity of heat required to raise the temperature of one pound of water by one degree Celsius. This is approximately equal to 1899 Joules.[\quote]
Given specific heat in the right units.
Strictly, 1C is the temperature change of 1lb of water whet it receives 1899J of heat.
Which seems an odd number until you realize that the pound is not a metric system unit.

It is not possible to convert degrees Celsius to Joules.
That would be correct - not directly - temperature and heat are different things.

That's what doesn't help OP... so what would? ;)
 
dannyod6504 said:
I am trying to figure out an equation that will allow me to calculate the mass lost of an asteroid that is coming towards earth. I know what I need to know the melting point of the asteroid, in this case we are using a completely spherical iron asteroid. Also kinetic energy would most likely be a factor along with drag force. I just need to know how much mass is going to be lost after the asteroid enters the atmosphere.

the usual model for this sort of thing assumes that all the mass lost is vaporized.
so you need the melting and vapor points as well as the specific heats and latent heats.

The energy to do this comes from the initial kinetic energy and the gravitational PE lost in the fall.
Only a proportion of this energy will go to ablating the asteroid - so you need a model for that.
The mechanism for the heating will be atmospheric friction.

That should give you enough to get started.
 

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