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Asked by mr brightside to Arthur, Clare, Daniel, David, Tora on 12 Nov 2014.
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Arthur Dyer answered on 12 Nov 2014:
Nice question!
This was actually looked at on mythbusters (an AWESOME programme if you’ve never seen it where they look to see if myths are true or not)
They found the terminal velocity (the maximum speed an object can fall at) of a coin was about 65 Miles Per Hour (MPH) and that that speed would leave an imprint on concrete but wouldn’t do much damage… in fact I think they even ended up shooting the coins at each other at 65 MPH and it didn’t do them any damage.
If you happened to be looking up and it hit you in the eye it probably wouldn’t be great but because it can only go 65mph maximum it can’t travel anywhere near as fast as a bullet.
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Tora Smulders-Srinivasan answered on 12 Nov 2014:
Arthur’s got a great answer to that one! I wouldn’t have thought a coin could do that much damage even from a very tall building. Not something to try on a poor passer-by though! 🙂
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Daniel Parsons answered on 12 Nov 2014:
Depends on how big and how streamlined the coin is! But if we are talking a 10 pence piece for example then the answer is no…
All dropped objects are pulled by gravity and experience a constant acceleration – that is….they go faster and faster and faster at a rate of about 10 metres per second, every second. In a vacuum after 10 seconds it would be travelling at about 100 meters a second. But air resistance plays a big role in slowing down a falling object. When air resistance matches gravity, the object reaches a terminal velocity – a maximum speed, after which it no longer goes any faster. At a weight of 10 grams, a 10 p coin would reach a maximum terminal velocity of about 20 km/h – that would hurt, likely cut your head by is not fast enough to kill you.
But if the coin is shaped like a bullet….well air resistance is much less and it will go much faster!
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