Can a penny dropped from a tall building kill a person?
This myth has been disproven many times, including on the TV show MythBusters in 2003.
Gravity provides a constant acceleration source to any dropped object – that is, in the absence of any other forces or resistance, a dropped object will continue to accelerate until it hits the ground. A penny dropped in a total vacuum from a skyscraper such as the Empire State Building could reach a speed of about 200 MPH.
In the real world, air resistance slows the penny’s descent. The thin, flat shape of a penny is not very aerodynamic – it tends to flutter back and forth like a leaf when falling. A dropped penny might reach 40 – 50 MPH at most.
Another factor is the very light weight of the penny. Even if it reached its maximum theoretical speed, the coin could cause pain if it struck your head, but it would certainly not kill you. MythBusters demonstrated that a penny fired from a rifle at 700 MPH still did not have enough energy to penetrate a human skull.
A penny released from the roof of the aforementioned Empire State Building would probably never even reach the ground at all – due to wind updrafts and the 83rd floor which juts out far enough to catch any dropped objects.
