The Velocity $\mathrm{v}$ In Feet Per Second of a Free- Falling Object Can

The velocity $\mathrm{v}$ in feet per second of a free- falling object can be found using the formula $\mathrm{v}=\sqrt{64 \mathrm{~d}}$ , where $\mathrm{d}$ is the distance (in feet) that the object has already fallen. Find the velocity of an object that has already fallen 210 feet. Round to the nearest foot per second.

A) $14 \mathrm{ft} / \mathrm{s}$
B) $17 \mathrm{ft} / \mathrm{s}$
C) $82 \mathrm{ft} / \mathrm{s}$
D) $116 \mathrm{ft} / \mathrm{s}$