$(10\backslash \%)$ Problem $8$: A disk of radinsRis sprayed with a charged paint so that the resulting charge density varies continually with radial distance,r$,$ from the center of the disc according to $\backslash [\backslash$sigma$=\backslash$omega $\backslash$frac$\{$r$\}\{$R$\}\backslash ]$ Observation pointPis located on the symmetry axis at a cistancehabove the plane of the disc, as sbown o $4$ ifR$=7\mathrm{.}15$cm$,$h$=6\mathrm{.}17$cmand$0=5\mathrm{.}38$nC$/$m$2,$ then what is the potential, in volts, at observation pointP? $\backslash [$ V$=\backslash ]$