Hey guys, so I'm back in school after an 8-month break, and I'm feeling a bit rusty(adsbygoogle = window.adsbygoogle || []).push({});

So I've got a flat disc of radius A, with constant density p, in the z=0 plane. I want to calculate the gravitational field at any point up or down the z-axis.

I integrated the potential over the disc got the correct potential function (which is given) of :

[tex]\Phi(z)=-G\rho2\pi(\sqrt{a^2+z^2}-z)[/tex]

So now I just take the negative derivative of this to get the Gravitational field, right?

[tex]G(z)=-\nabla\Phi(z)[/tex]

[tex] G(z)=-G\rho2\pi(\frac{z}{\sqrt{a^2+z^2}}-1)[/tex]

But this means there is a force at z=0 when I think there should not be...

[tex]How do I make a new line in Latex? \\ this doesn't seem to work? :@[/tex]

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# Homework Help: Gravity of a Flat Disc

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