At highway speed’s, a particular automobile is capable of an acceleration about 1.6 mi./s. At this rate how long does it take to accelerate from 22 mi./s to 31 mi./s?
surely you mean m/s, not mi/s !!
Since a = ∆v/∆t that means that
(31-22 m/s)/t = 1.6 m/s
t = 9/1.6 = 5.625 s
velocity is just a linear function of time, where acceleration is the slope.