A car traveling in a straight line has a velocity of +8.5 m/s. After 3.5 s, its velocity is +9.0 m/s. What is the car's average acceleration in this time interval?
Just give it a little thought:
in 3.5 seconds, the velocity changed from 8.5 to 9.0m/s
it took 3.5 seconds to change by 0.5 m/s
0.5m/s / 3.5s = 0.14m/s^2