as the car is changing its velocity per seconds hence acceleration will be produced now we have to find average acceleration which is equal to <a>=total change in speed/total time
as car is moving with initial velocity 10m/s and final velocity 30m/s
total time is 8 sec
now <a>=final-intial velocity/toatal time
=30-10/8
=2.5 m/sec^2
hence the average velocity of car is 2.5m/sec^2
