#### Answer

$H=81l^{2}w^{2}$

#### Work Step by Step

Since $H$ is jointly/directly proportional to the squares of $l$ and $w$, we have:
$H=kl^{2}w^{2}$
We are given: $H=36$ and $l=2$ and $w= \frac{1}{3}$, so we have:
$36=k(2)^{2}( \frac{1}{3})^{2}=k*4*\frac{1}{9}$
$36=\frac{4}{9}k$
$k=36*9/4=81$
So the equation is:
$H=81l^{2}w^{2}$