Answer
$W=\dfrac{360}{r^2}$
Work Step by Step
$W$ is inversely proportional to the square of $r$ so the equation that relates the variables is:
$W=\dfrac{k}{r^2}$ where k = constant of proportionality.
If r = 6, then W = 10. Substitute these values into the equation above to have:
$WS=\dfrac{k}{r^2}
\\10 = \dfrac{k}{6^2}
\\10=\dfrac{k}{36}
\\10(36)=k
\\360=k$
The constant of proportionality is $360$. Thus, the equation that relates W and r is:
$W=\dfrac{360}{r^2}$
