The Mike O’Callaghan-Pat Tillman Memorial Bridge spanning the Colorado River opened on October 16, 2010. Having a span of 1900 feet, it is the longest arch bridge in the Western Hemisphere, and its roadway is 890 feet above the Colorado River.

If a rock falls from the roadway, the function $s=$ $f(t) =16t^{2}$ gives the distance $s$, in feet, that the rock falls after $t$ seconds for $0 ≤ t ≤ 7.458$. Here, $7.458$ seconds is the approximate time it takes the rock to fall $890$ feet into the river. The average velocity of the rock during its fall is $$\dfrac{\Delta s}{\Delta t}=\dfrac{f( 7.458) -f(0) }{7.458-0}=\dfrac{890-0}{7.458}\approx 119.335\; \hbox{feet per second}$$