A penny dropped from the top of a skyscraper will not kill anyone. As it falls, air pushes back harder the faster it goes, until that push balances gravity and it stops speeding up — its terminal velocity. For a light, tumbling penny that limit is only about 11 metres per second, the speed of a thrown pebble. It would sting if it hit you, no more. A streamlined steel dart is a different story — shape and air, not height, decide.
Most people think a penny dropped from a skyscraper hits like a bullet. In fact air drag caps a tumbling penny at about 11 m/s, the speed of a thrown pebble, so the extra height adds nothing and it would only sting.
What's actually happening
The image is irresistible: a coin tossed from a great height, accelerating all the way down, striking the pavement (or an unlucky pedestrian) with deadly force. It treats falling as endless acceleration — and in a vacuum it would be. But we don't fall in a vacuum. We fall through air, and air pushes back, harder and harder the faster you go.
That push is drag, and it grows with the square of speed. Drop a penny and at first gravity wins and it speeds up — but as it accelerates, drag climbs until it exactly cancels gravity. From that moment the penny falls at a constant terminal velocity, no matter how much farther it has to go. For a penny the numbers are humbling: it's light, it has a lot of surface area for its weight, and it tumbles chaotically rather than slicing through the air, all of which crank up the drag. Its terminal velocity is only about 11 metres per second — roughly the speed of a firmly thrown pebble. The simulator shows it plateau almost immediately; the other 380 metres of skyscraper add nothing. MythBusters tested this directly and confirmed: a penny to the face stings, and that's the whole danger.
The myth isn't wrong because falling objects are harmless — it's wrong because it ignores shape. Swap the penny for the steel dart in the simulator and watch it keep accelerating: dense and streamlined, it has a low drag coefficient and a terminal velocity many times higher, easily into injury territory. A dropped pen, bolt, or screwdriver genuinely is dangerous from height. So the real lesson is that what kills isn't the drop — it's the aerodynamics. A penny is, fortunately, one of the worst-shaped projectiles imaginable.
What kills a falling object is its aerodynamics, not the drop — a penny is one of the worst-shaped projectiles imaginable, but a dense, streamlined dart is a different story.
- 1Drop a coin and a flat sheet of paper from the same height — the paper flutters down slowly, all drag.
- 2Now scrunch the paper into a tight ball and drop again: it falls much faster. Same paper, same weight — you only changed its drag.
- 3That difference is terminal velocity in your hand. The penny is closer to the flat-paper end than people imagine: light, draggy, and capped at a gentle speed.
Common questions
Once the penny reaches terminal velocity it falls at a constant speed no matter how much farther it has to go. It plateaus almost immediately, so the other 380 metres of skyscraper make no difference.
No — what matters is shape, not height. A dense, streamlined object like a steel dart, pen or bolt keeps accelerating to a far higher, genuinely dangerous terminal speed. A penny is one of the worst-shaped projectiles imaginable.
Yes. MythBusters fired pennies at terminal speed and confirmed a penny to the face merely stings — and even one shot faster than it could ever naturally fall did not break skin.