Falling PennyCan it really kill a person if dropped by the Empire State Building?

Wahhaj Iqbal Butt

The Myth

A penny can penetrate the sidewalk and could kill a person if it drops on the head. If it is dropped from the Empire State building.Could this be true? Lets apply physics to find out.

The Physics

In Kinematics we learn that a falling object, in this case the penny falls with the acceleration of g, which is 9.82 m/s2. While the penny is dropping the forces acting on penny are shown by the diagram.But as the penny keeps on falling. There is a point where the forces air resistance and weight due to gravity cancel each other out. The penny is now at its terminal velocity.The terminal velocity of a penny is hard to find out as while the penny falls it could fall in different ways. It could fall flat or could tumble on its way. Therefore we can make an estimate from the table. The terminal velocity of a penny should be some where between 9 – 20 m/s (32-72kph)Is this velocity enough to kill you? Lets find out.

Air Resistance

Weight

The Skull

In order for the penny to kill you, it has to penetrate your skull. The maximum force that the skull can withstand is approximately 85000 Newton's.The maximum force a penny could have after the terminal velocity is less than 85000 Newton’s. If and only if air was removed from New York, then the speed could be dangerous.

Conclusion

This myth is definetly busted. The falling penny could sting you but it is not lethal enough to kill you. The worst case scenario the penny falls into your eye, but still the force will not be enough to take your eye out.

SOURCES

• http://cache.lego.com/e/dynamic/is/image/LEGO/21002?$main$• http://

www.fieldandstream.com/files/imagecache/photo-article/photo/38356/f25c08e08f6589f80e3138a5db1db061.jpg• http://www.livescience.com/6040-brute-force-humans-punch.html• http://

www.rudyard.org/wp-content/uploads/2013/09/human-skull-front.jpg• http://excamera.com/sphinx/_images/watterott1.png• http://www.gantless.com/paper.html• https://www.youtube.com/watch?v=PHxvMLoKRWg• https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcS3-nluIBLttEYVD

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