Answer:
Acceleration of the car will be 
Explanation:
We have given that car starts from rest so initial velocity of the car u = 0 m/sec
And car traveled 400 m in 10 sec
So distance traveled by car s = 400 m
Time taken to compete this distance t = 10 sec
We have to find the acceleration of the car
From second equation of motion we know that 
So 

So acceleration of the car will be 