Answer
a) The stopping distance $D(v)=0.05v^2+2.6v-15$
b) $D(60)=321$
c) A vehicle travellng at a speed of $60 \text{ miles per hour}$ will need a stopping distance of $321$ feet.
Work Step by Step
Given,
Reaction distance $R(v)=2.2v$
Breaking distance $B(v)=0.05v^2+0.4v-15$
a) The stopping distance is calculated as below
$D(v)=R(v)+B(v)$
$=2.2v+0.05v^2+0.4v-15$
$=0.05v^2+2.6v-15$
b) Substitute $x=60$, To calculate the stopping distance at 60mph,
$D(60)=0.05(60)^2+2.6(60)-15$
$=180+156-15$
$=321$
c) The car will need $321$ feet to stop once the impediment is observed.
