To solve this we are going to use the free distance fallen formula: 
where
is the distance
is the gravity of Earth 
is the time in seconds
We know from our problem that the penny fell off the top of the building and hit the sidewalk below 3.1 seconds later, so
. Lets replace the value in our formula:
meters
We can conclude that the penny fell a distance of 47.098 meters
where
We know from our problem that the penny fell off the top of the building and hit the sidewalk below 3.1 seconds later, so
We can conclude that the penny fell a distance of 47.098 meters