Now we have to find the derivative:
[tex]\begin{gathered} \left(2h\right)dh/dt\frac{}{}\text{ = 2x \lparen}\frac{dx}{dt}) \\ \frac{dh}{dt}\text{ = 2 \lparen8m/s\rparen / 2 \lparen32\rparen} \\ \frac{dh}{dt}\text{ = }\frac{16}{64} \\ \frac{dh}{dt}\text{ = }\frac{1}{4} \\ ^{=\text{ 0.25m/s}} \end{gathered}[/tex]The rate of change is 0.25m/s