Suppose you increase your walking speed from 5m/s to 14m/s in a period of 1. what is your acceleration?

Acceleration = (change in speed) / (time for the change.

change in speed = (ending speed) - (starting speed) = 9 m/s.

Acceleration = (9 m/s) / (period of 1).

We don't know the units of the 'period of 1'.

If it means '1 second', then the acceleration is 9 m/s².