If you've ever been at the top of a large building with a group of people, there's usually that one person that says "what if I spit from here?" or "what if I dropped a coin right now?". Well, people usually warn against these acts for fear of hurting a pedestrian down below. The question is, how badly could dropping a coin hurt somebody if this were to happen?
In reality, the coin could not hurt somebody very badly. Coins are very light weight, as a penny weighs around 1 gram, and tumble end over end as they fall. Because of this, they don't pick up much speed against air resistance before reaching terminal velocity. The terminal velocity of a penny is only about 40-50 MPH. This means the coin would be traveling at a relatively slow speed as it approaches the ground. If it were to make direct contact with a pedestrians head, it would obviously hurt a bit, but would not cause significant injury, and definitely would not lead to death. All in all, dropping a penny from this height will hurt about as badly as it would if you threw it at someone's head from a short distance away. So the next time some wise guy tries to tell you you'll kill someone if you drop a penny from such a height, whip out some physics knowledge to counter their point.