Ok, I need to find the frictional force on sphere of radius [itex]a[/itex] and mass [itex]M[/itex] moving with velocity [itex]v[/itex] in an ideal gas at temperature [itex]T[/itex].(adsbygoogle = window.adsbygoogle || []).push({});

If I put myself in the sphere frame, then diffrential cross-section is

[tex]

\frac{d\sigma}{d\Omega} = \frac{a^2}{4}

[/tex]

and the total cross-section is [itex]\sigma_{\textrm{tot}}=\pi a^2[/itex]. How do I find the frictional force from this? Ellastic collisions between the sphere and the gas particules are assumed.

Any help greatly appreciated.

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# Homework Help: Frictional force on a sphere

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