I don't live in the USA, and even I have heard this one. And in some way it makes sense that something that is able to fall from so high up, must come down with serious force....perhaps even enough to kill a person on the ground!!
I mean if this was the case, all the tall buildings in the world would perhaps have a fence around the top that would stop anything being chucked off it then wouldn't they?
Something small like a nut or bolt falling from a high place would really hurt you! This is the reason people wear hardhats on sites...for the falling debris and stuff that could seriously injure them.
To give you an idea, a bullet is a tiny piece of metal that weighs in at 5 to 10 grams. That really is not heavy at all.
However, when fired from a gun at speeds of between 800 to 2000 mph (1250 - 3200 kph) depending on the type of weapon and powder used, the 'weight' or even better, the energy of that tiny little bullet suddenly becomes more than enough to kill a person.
the momentum gives the energy, and the bullet is so small that the energy is concentrated on such a small point with great force!
Just a little science reminder about energy. Kinetic energy is related to the square of the objects velocity. This means that if the object travels at 2x its speed, the object in fact gets 4x the kinetic energy!
So a car travelling 1km/h has quite a bit of momentum or kinetic energy because its weight is quite high, but at 2km/h it has 4x the momentum or kinetic energy....a lot more difficult to stop.
The damage from something weighing hardly anything...kinetic energy!
The Facts
Well just how fast does a penny or coin hit the ground when falling from a high building like that?
A penny will fall at the speed of 64 mph (102kph). This is largely because of the shape of the coin. Being flat and not weighing that much, the air resistance on the coin stops it from falling any faster than that.
This will still hurt a person if it hit them on the head, maybe even break the skin if it hits the head at the right angle.
If the shape of the coin was different, and had a little more weight to it....lets say like a 50g nut head, this would be a different ball game altogether.
Now you're talking about something that would fall at around 200mph (320kph) and hit a person or ground with a force of about 100 foot pounds (1 foot-pound is the amount of energy needed to raise 1 pound 1 foot in the air) or 0.5kgs to a height of 30m into the air.
More than enough to kill a person!
Mythbusters in fact took this test quite far, by setting up a nail-gun to shoot a coin at terminal velocity into a simulated skin.
The results supported the science, showing that the coin just doesn't have the energy to really hurt someone while falling from any height.
They even mentioned that even if looking straight up at the sky with the coin hitting you squarely in the eye, it would most probably not really damage the eye.
Check out the video below....this myth is busted!!
