$$ F=ma $$ $$\sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6}$$
$$ S_{i+1} = S_i * (1 + r) $$
$$1+r = S_{i+1}/S_i$$
$$r=S_{i+1}/S_i-1$$
$$S_{i+2} = S_i * (1+r)^2$$
$$(1+r)^2 = S_{i+2}/S_i$$
$$r=\sqrt S_{i+2/S_i})-1$$
$$ F=ma $$ $$\sum_{i=0}^n i^2 = \frac{(n^2+n)(2n+1)}{6}$$
$$ S_{i+1} = S_i * (1 + r) $$
$$1+r = S_{i+1}/S_i$$
$$r=S_{i+1}/S_i-1$$
$$S_{i+2} = S_i * (1+r)^2$$
$$(1+r)^2 = S_{i+2}/S_i$$
$$r=\sqrt S_{i+2/S_i})-1$$