Recent content by andyfry

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    Hot air balloon - Ideal gas law

    Ah, that might help! rearranging (properly!) for Tin now gives an answer of 450k, which I believe is the right answer. Thanks a lot for your help! :)
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    When do quantum effects become important?

    Pretty sure this is correct. Would be great if someone could just confirm please?
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    Hot air balloon - Ideal gas law

    well mair=nM where M=molar mass of air so subbing into pV=nRT gives mair=\frac{pVM}{RT} Is this what you mean? Can't really see how this is helpful though. Still leaves me with unknowns of p, \rho, and M after subbing into intitial equations. How does using the molar mass of air, M...
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    Hot air balloon - Ideal gas law

    Homework Statement Estimate the required temperature of the air inside a (rigid) balloon in order for it to achieve lift off. Volume 2000m3 \summass, mtot=920kg Homework Equations pV=NkT p=\frac{Force}{Area} \rho=\frac{m}{V} The Attempt at a Solution We require Fup>(mair+mtot)g (assume...
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    When do quantum effects become important?

    Yeah, this was what I was trying to do! Thought i had solved it correctly and was just looking for confirmation. However I've now noticed I got a few dimensions confused. I'll try again... Multiplying G and \hbar gives dimensions of L5T-3. c-3 will have dimensions L-3T-3 (I believe?) So...
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    When do quantum effects become important?

    At what length scale do quantum effects become important in gravitational calculations??