how to find velocity average? Difference between velocity average and final velocity?

Question

A car starting from rest accelerates to the left. It takes 14 seconds to travel a distance of 20 meters. What is the car's average velocity?

I'm really confused by this question I'm not sure whether to use change in displament divided by change in time or (Velocity Initial + Velocity Final)/2?

Answer 1

In this situation, the average speed is just the distance traveled divided by the time interval.

 

v_av = d/t = (20 m)/(14 s) = 20/14 m/s ≅ 1.43 m/s