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Thread: Can anyone answer this question for me?

  1. #1 Can anyone answer this question for me? 
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    At 80,000 feet, how fast do you have to be traveling to produce enough friction to melt titanium?

    If anyone can answer that or tell me how to figure it out, it would be very helpful.

    Thank you.


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  3. #2 Re: Can anyone answer this question for me? 
    Forum Senior Yash's Avatar
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    Quote Originally Posted by Jshep08
    At 80,000 feet, how fast do you have to be traveling to produce enough friction to melt titanium?

    If anyone can answer that or tell me how to figure it out, it would be very helpful.

    Thank you.
    You see, melting point of titanium is 1668 C. That itself is quite high.
    Also, you should mention what amount of titanium are you calculating for, from 24 Km ??

    :-D


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  4. #3  
    Forum Senior Yash's Avatar
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    Note: Post your question in their respective section, like this should have been in Physics
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    Sorry i haven't got any idea as i never went 80000 feet height
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  7. #6  
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    By friction do you mean drag from air?
    Be sure to use SI units:
    Force= 0.5*air density*drag coefficient *cross sectional area of object moving through the air*velocity^2

    Work=force*distance

    The work the air is doing on the object converts kinetic energy (decelerating it) into enthalpy.

    Temperature increase =
    Work/(25.06*moles of titanium)= change in temperature

    Moles of titanium= grams of titanium/47.867


    These are the basics of what you would need to know to do the calculations. I simply took values from wikipedia.
    Pick all the values you want (initial temperature of the titanium, distance the titanium is traveling through the air, etc). You should be able to look up values you need (such as density of the air).
    The melting point of titanium would also vary depending on the pressure; you could factor this in as well.

    This is simplified; the titanium would also be transferring and radiating away heat. Would probably be a good idea to incorporate this as well.

    My understanding of physics is quite basic, so someone else would likely be able to help more with this.
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  8. #7  
    Forum Professor jrmonroe's Avatar
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    There's no easy answer to this. How aerodynamic is the shape of the titanium? That is, what's its coefficient of drag? What is its surface roughness? How thick is the titanium? Is it actively cooled? How? What's behind the titanium? Etc, etc. Even though I don't know how to compute the answer for you, I've studied aerodynamics,, and it's much more complex than the original question.
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