To the editors:
Cecil Adams’s answer about which bullet hits the ground faster [Straight Dope, December 16] is right, but for the wrong reasons. There is a much stronger reason than curvature of the earth why the dropped bullet hits the ground faster than the fired one, namely air resistance.
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Air resistance is a force which tends to slow down an object, and its strength is roughly proportional to the square of the speed of the object. A dropped object takes quite a distance to get up speed (the formula is speed equals the square root of 2 x g x distance, where g is gravity and is 32 ft/sec(2), so after dropping 100 ft, an object would be going the square root of 6400 or 80 feet per second, not counting air resistance). On the other hand, the fired bullet starts out really fast–probably about 1000 ft/second.
I’m not sure you want to try to explain this to your readers, but good luck making a coherent explanation if you do. By the way, I’m not a physicist, but I did take quite a lot of physics in college.
