The actual speed of the car at the top of the hill is 20.0m/s. What is the reason for this difference in velocity?

Please find the answer in the explanation.

Explanation:

Given that the actual speed of the car at the top of the hill is 20.0m/s. What is the reason for this difference in velocity?

Speed is a scalar quantity that is, it has only magnitude but no direction.

While velocity is a vector quantity, that is, it has both magnitude and direction.

If the actual speed of a car is 20 m/s, that is the magnitude of the speed only without direction.

The velocity will therefore be of the same magnitude but with addition of direction. Either west, east or north south.