The urban legend of a penny dropped from the top of the Empire State Building becoming a lethal projectile is a widely circulated tale. Many believe that such a small object, falling from immense heights, would gather enough speed to cause serious injury or even death. This popular notion often conjures images of a penny piercing concrete or embedding itself in a skull. This article investigates the scientific truth behind this persistent urban legend, exploring the fundamental physics that govern falling objects.
The Science of Falling Objects
All objects falling towards Earth are initially pulled downward by gravity, which causes them to accelerate. However, as an object gains speed, it encounters an opposing force known as air resistance, or drag. This resistance arises from collisions with air molecules and increases significantly as the object’s velocity rises.
Eventually, a balance is reached where the upward force of air resistance equals the downward pull of gravity. At this point, the object stops accelerating and continues to fall at a constant maximum speed, called its terminal velocity. The specific terminal velocity an object reaches depends on several factors, including its mass, shape, and surface area. A lightweight, irregularly shaped object like a feather, for instance, has a much lower terminal velocity than a dense, streamlined object like a rock.
The Penny’s Actual Journey and Impact
Applying these principles to a penny reveals a very different outcome than the urban legend suggests. A penny is a relatively light object with a flat shape, meaning it experiences substantial air resistance for its small mass. Consequently, a penny reaches its terminal velocity rapidly, typically within 50 to 85 feet of its fall.
Once it reaches this maximum speed, a penny will continue to fall at a constant rate, generally estimated to be between 25 and 70 miles per hour. At this speed, the impact of a falling penny would be comparable to a flick on the forehead or a light tap. While it might sting or cause minor discomfort, it lacks the force to cause serious injury, penetrate skin, or damage a skull. Experiments confirm that even at its terminal velocity, a penny cannot break concrete or human bone.
The environmental conditions around a tall structure like the Empire State Building would influence the penny’s descent. Strong wind currents, common at such heights, would likely blow the lightweight penny significantly off its vertical path. This makes a direct hit highly improbable, even if it were a more dangerous projectile.
Why the Myth Endures
The persistence of this myth often stems from a common misunderstanding of physics. Many people assume that an object continuously accelerates as it falls, without accounting for the effect of air resistance. This flawed intuition leads to the incorrect conclusion that objects falling from extreme heights achieve dangerous speeds.
The visual drama associated with dropping something from a towering skyscraper also contributes to the myth’s longevity. The scale of the fall amplifies perceptions of danger, making the exaggerated outcome seem plausible. Urban legends often thrive on compelling narratives bypassing scientific scrutiny. The story of the penny is a prime example of how a simple, yet inaccurate, tale becomes ingrained in popular culture.