Mary travelled 70 miles/hour due north. this is an example of what?

velocity.

Explanation:

Velocity is a vector quantity, which consists of:

- a magnitude, which is equal to the ratio between the displacement of an object and the time taken for the displacement to occur:

- a direction, which is equal to the direction of the displacement

In this case, we are given both the magnitude (70 miles/hour) and the direction (north), so this is an example of velocity.

causes

fossil fuels burn

cities become more industrialized

human population grows worldwide

3. dark matter

empty space could also be a simple vacuum