Answer:
Quadratic
Explanation:
It's not linear because the speed of the penny is not constant.
It is not exponential because the speed does not continuously increase at a faster rate.
It is Quadratic because the penny will increase speed as you throw it up into the air. Once it reaches its "high point" it's speed hits 0, which is the origin of the quadratic equation. Then the speed increases faster and faster as it falls.