\(F' = \frac{{\left( {m + \frac{m}{2}} \right)\,\,{{\left( {v + \frac{v}{2}} \right)}^2}}}{{\left( {r + \frac{r}{2}} \right)}}\) \(= \frac{9}{4}\frac{{m\,{v^2}}}{r}\)
\(\therefore F' = \frac{9}{4}F\)
\(\frac{{\Delta F}}{F} \times 100\,\, = \frac{{F'\, - F}}{F} \times 100\% \, = \frac{{500}}{4}\% = 125 \,\%\)
$\text { [ } \left.g=10 \mathrm{~ms}^{-2} \mathrm{\epsilon}\right]$