8. a car travels from town a to town b on one road at different speeds and stops at red lights. if you know the distance between the towns and the total time of the trip you can calculate the

The velocity

Explanation:

The difference between speed and velocity is the following:

- Speed is defined as the ratio between the total distance covered by an object and the time taken:

and it is a scalar.

In this problem, we cannot calculate the speed of the car, because we don't know exactly what is the distance covered by the car (we only know the distance between town A and town B, but we don't know if the car has travelled on a straight path or not, so we don't know the distance it has covered)

- Velocity is defined as the ratio between the displacement and the time taken:

(note that velocity is a vector)

Displacement is the shortest distance (straight line) between the final and the initial point of the motion: in this case, it corresponds to the distance between town A and town B, which we know. Since we also know the time of the trip, this means that we can calculate the velocity of the car.