Falling Pennies Are No Real Threat to Innocent City Sidewalk-Walkers

Due to the physical forces acting on it, studies show that a penny falling from a skyscraper would not cause any serious injury to people on the sidewalk below

Article: http://www.scientificamerican.com/article.cfm?id=could-a-penny-dropped-off

Image: google images

Louis Bloomfield, a University of Virginia physicist, recently conducted research to provide a definite answer to the falling penny turned dangerous weapon myth. He replicated the skyscraper scenario using wind tunnels and helium balloons. Ultimately, he found that the small, flat shape of the penny prevented it from becoming a torpedo, forcing it to flutter harmlessly to the ground instead. People who believe the myth assume that the force of gravity on the penny accelerates it to a dangerous speed during its descent. However, this could only happen in a vacuum. As it is, the penny’s flat surface collides with air molecules which slow it down. Air resistance creates a “drag force” which counteracts gravity. As gravity makes the penny fall faster, the air resistance increases. At maximum velocity, the air resistance and gravity working on the penny are equal and opposite, making the penny fall at a constant speed, or terminal velocity, until it reaches the sidewalk (or a passerby). This terminal velocity, 25 mph, is reached after about fifty feet. In a vacuum, the penny would reach a speed of 208 mph, which could cause damage to a skull. Though a falling penny has been proved harmless by this study, the same cannot be said of ballpoint pens. If a pen was thrown off a skyscraper and happened to have a design which caused it to shoot down like an arrow, it could hit the ground at 200 mph, causing quite a bit of damage.

This study may not earth-shattering or exactly life saving. However, our generation is interested in myth busting (the success of the show Myth Busters acts as evidence to this claim). We have all heard the warning not to throw anything off very tall buildings for the safety of those below. This warning remains valid. However, the myth which was created as a result of this warning has been busted by Bloomfield’s study. Now, when one has the urge to litter from the top of the Empire State Building, we know to throw harmless pennies and definitely not writing utensils.

I was drawn to this article because it mixes humor and pop culture with science. Many of the articles I’ve read for this assignment are interesting, but very serious. Some are more exciting, detailing new discoveries about the human body or a new species of animal, but they are rarely very funny. The title of this article made me laugh. I have heard the falling penny myth many times and even saw it in action during a performance of Avenue Q. I enjoyed learning what it was that made this myth untrue and how it can be applied instead to objects like ballpoint pens. I may no longer have to beware falling penny-torpedoes, but those pen-arrows sound pretty terrifying. Thankfully, I don’t have much to worry about in Clemson.