Would a penny dropped from the Empire State Building kill someone on the ground?
I have this friend and he isn't playing with a full deck, if you know what I mean, and he said if you drop a penny from the top of the Empire State Building and it happened to hit someone in the head it would go through just like that. Is this true?
You're thinking: I see a great opportunity for an experiment. Eh, maybe not. The Empire State folks, for their part, claim no one has ever dropped anything off their building. Seems doubtful, but never mind. If scientists can noodle out the origins of the cosmos based strictly on theory, I don't see what's so tough about this.
Given that the Empire State Building is 1,250 feet tall and ignoring such factors as wind resistance for the moment, a penny dropped from the top would hit the ground in approximately 8.8 seconds, having reach a speed of roughly 280 feet per second. That's not particularly fast. A low-powered .22 or .25 caliber handgun bullet, to which a penny is roughly comparable in terms of mass, typically has a muzzle velocity of 800 to 1,100 FPS, with maybe 75 foot pounds of energy.
On top of this we must consider that the penny would probably tumble while falling, and that the Empire State Building, like all tall buildings, is surrounded by strong updrafts. These would slow the penny's descent. Thus while you might conceivably inflict a fractured skull on some hapless New Yorker (or, more likely, some cretinous tourist from Towson), the penny wouldn't "go through just like that." I bet it wouldn't even penetrate the skin. Not that I intend to find out.
(For further discussion, see "Can a bullet fired into the air kill someone when it comes down?")