b
(b)Here \(\frac{{m{v^2}}}{r} = \frac{K}{{{r^2}}}\)
K.E.\( = \frac{1}{2}m{v^2} = \frac{K}{{2r}}\)
\(U = - \int_\infty ^r {F.dr} = - \int_\infty ^r {\left( { - \frac{K}{{{r^2}}}} \right)} \,dr = - \frac{K}{r}\)
Total energy \(E = {\rm{K}}{\rm{.E}}{\rm{.}} + {\rm{P}}{\rm{.E}}{\rm{.}} = \frac{K}{{2r}} - \frac{K}{r} = - \frac{K}{{2r}}\)