$$P= \frac{ m }{ (1/3) \pi { r }^{ 2 } h }$$
$P=\frac{3m}{\pi hr^{2}}$
$h\neq 0\text{ and }r\neq 0$
$\left\{\begin{matrix}h=\frac{3m}{\pi Pr^{2}}\text{, }&m\neq 0\text{ and }r\neq 0\text{ and }P\neq 0\\h\neq 0\text{, }&P=0\text{ and }m=0\text{ and }r\neq 0\end{matrix}\right.$
