The saying "What goes up must come down" is an appropriate starting point. If you fire a gun into the air, the bullet will travel up to a mile high — depending on the angle of the shot and the power of the gun. Once it reaches its highest point, the bullet will fall. Air resistance limits its speed, but bullets are designed to be fairly aerodynamic, so the speed is still quite lethal if the bullet happens to hit someone. In rural areas, the chance of hitting someone is remote because the number of people is low. In crowded cities, however, the probability rises dramatically, and people get killed quite often by stray bullets. So, how high will a bullet go and what stops it and sends it falling back to earth? Studies have shown that a standard .30 caliber bullet fired from a rifle pointed straight up will rise to an altitude of 9,000 feet in 18 seconds, and then will return to earth in another 31 seconds. During the last few thousand feet, it will attain a nearly constant speed of 300 feet per second. No matter how high a bullet goes in the air, it will eventually decelerate until its velocity reaches zero, at which point it will begin to fall back to earth. A bullet is unlikely to fall straight down, as wind can alter its path. That makes it difficult to predict exactly where a bullet will land. Many states have laws against celebratory gunfire, which is when most bullets fired into the air occur.
