Homework Statement
work out g field at a distance r=R/2 from the centre of a spherically symmetric body of radius R.
Homework Equations
\nabla^{2}\psi=4\pi G \rho
\psi=G\int_{V'}\rho\frac{1}{|\vec{r}-\vec{r^{'}}|}d^{3}\vec{r^{'}}
-\int_{V}\nabla\cdot g dV = \int_{V}\rho dV...