Answer:
1 second later the vehicle's velocity will be:

5 seconds later the vehicle's velocity will be:

Explanation:
Recall the formula for the velocity of an object under constant accelerated motion (with acceleration "
"):

Therefore, in this case
and 
so we can estimate the velocity of the vehicle at different times just by replacing the requested "t" in the expression:

The correct answer is C) Rainfall
It is gravity¿ what is the question?
C. increased stirring i think