I'm a bit lost don't know why. We defined the potential $u_{\mu}$ of a Radon measure $\mu$ as the convolution of the meaure with the logarithm:
$u_{\mu}(x)=-\int \log|x-y| d\mu(y) $
and the energy $I(\mu)$ of the measure as the integral over the potential:
$I(\mu)=\int u_{\mu}(x)d\mu(x)$
I'd like to compute the energy of the Lebesgue measure restricted to a compact ball $\overline{B}_R$.