A Truck Is Traveling Down a Steady Slope Such That $1 \mathrm{~m}$

A truck is traveling down a steady slope such that for each $1 \mathrm{~m}$ the truck goes forward along the slope it goes down $0.04 \mathrm{~m}$ (we call this a $4 \%$ grade) . Imagine that the truck's brakes fail. What is the approximate increase in the truck's speed after $30 \mathrm{~s}$ , assuming that the engine is not used and there is little drag or other friction? $[\vec{g} \mid=$ $22(\mathrm{mi} / \mathrm{h}) / \mathrm{s}$ .]

A) $0.9 \mathrm{mi} / \mathrm{h}$
B) $11 \mathrm{mi} / \mathrm{h}$
C) $26 \mathrm{mi} / \mathrm{h}$
D) $53 \mathrm{mi} / \mathrm{h}$
E) $660 \mathrm{mi} / \mathrm{h}$
F) Other (specify)