When gasoline and water are poured into the same container, they form two distinct layers. what do you need to know to predict which liquid will be on top ?

Water and gasoline have different densities so they will never mix, regardless of which you put first.  

The gasoline will be the one on top because water is more dense.\

~*"AUBA14"*~

what is the average time it took the car to travel 0.25 meters?

⇒ 2.23 seconds

what is the average time it took the car to travel 0.50 meters?

⇒ 3.13 seconds