To solve this we are going to use the free distance fallen formula: [tex]d=0.5gt^2[/tex]
where
[tex]d[/tex] is the distance
[tex]g[/tex] is the gravity of Earth [tex]9.8m/s^2[/tex]
[tex]t[/tex] 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 [tex]t=3.1[/tex]. Lets replace the value in our formula:
[tex]d=0.5gt^2[/tex]
[tex]d=0.5(9.8)(3.1)^2[/tex]
[tex]d=47.089[/tex] meters
We can conclude that the penny fell a distance of 47.098 meters