## Algebra: A Combined Approach (4th Edition)

$256$ feet
Let $s$ be the speed of an anvil. Let $d$ be the distance of an anvil's fall. $s=k\sqrt d$ $s=160; d=400$ $160=k\sqrt {400}$ $160=k(20)$ $k=8$ $s=8\sqrt d$ $s=128$ $128=8\sqrt d$ $\sqrt d=16$ $d=256$ feet