You are out running and the first mile takes you 10 minutes. the second mile takes 20 minutes. this is an example of ?

Negative acceleration.

Explanation:

It is given that, you are out running and the first mile takes you 10 minutes. The second mile takes 20 minutes. Here, to cover same distance time increases. It is the case of negative acceleration or deceleration.

Similarly, if the distance travelled is same also the time taken to cover this distance is decreasing is called positive acceleration.

So, the above case is an example of negative acceleration. Hence, this is the required solution.