Given:
[tex]t=\frac{\sqrt[]{h}}{4}[/tex]To find the time when the height h=8100 feet:
Substitute h=8100 in the given function.
[tex]\begin{gathered} t=\frac{\sqrt[]{8100}}{4} \\ t=\frac{90}{4} \\ t=22.5\text{ seconds} \end{gathered}[/tex]Thus, the time required for the hammer to reach the river is 22.5 seconds.
