Naval soldiers prepare to fire a gun salute during a burial at sea. This would be catastrophically unsafe in any region where the bullets could come down and land on a human. Image credit: U.S. Navy photo by Mass Communication Specialist 3rd Class Kevin J. Steinberg.

Why firing a gun into the air can kill somebody

The physics of why popping off a few rounds in celebration can quickly turn deadly.

“I’ve heard it said that God made all men, but Samuel Colt made all men equal. We’d see what Mr. Colt could do for a woman.” -Cherie Priest

Would you fire a gun into the air in celebration if you knew that, when the bullet comes down, it could kill somebody? It’s no surprise that bullets fired towards a target can easily destroy whatever they run into: a bullet from an AK-47 leaves the rifle traveling at over 1,500 miles per hour (670 meters per second): about double the speed of sound. Despite only having a mass of about five grams — under a fifth of an ounce — it’s got the energy of a brick dropped from a 30 story building. Concentrated into a tiny surface area at the bullet tip, it can easily break through your skin. And once it does, that energy and momentum tears through your body, ripping a hole through blood vessels, muscle, and potentially vital organs. No wonder it can kill you.

A 0.50 caliber bullet wound of the face. The patient was injured while heating a 0.50 caliber incendiary machine gun bullet with a blowtorch in a World War II-era accident. Image credit: the National Museum of Health and Medicine.

But what if the bullet is fired up, rather than directly at a target? If you performed that experiment on the Moon, if the…