| MadSci Network: Physics |
I have to make an assumption to answer your question, and that is that the rifle's sight is being aimed level with the ground. If that is so, then the bullet actually does rise slightly, for most rifles. I say "most rifles" because most rifles have their sights mounted above the barrel. When a rifle's sight is adjusted, it has to be adjusted for a specified range. Refer to the following picture.
Because the sight is above the barrel and we want the bullet's path to cross the path of the sight, the barrel does in effect get aimed upward just a little bit. Then, as the bullet falls in its flight, it will cross the path of the sight a second time!! So there are two ranges at which the rifle is sighted!! I have a .22 rifle with a scope, and I have sighted in the scope at a range of 25 yards. It turns out that the second sight point (the secondary range) is about 75 yards for my rifle. The exact distances depend on the type of rifle and how high up the sight is from the barrel.
You can think of this as pointing the sight DOWN to make the sight's path cross the path of the bullet, but it is the same effect: if the sight is then pointed at a target the bullet will rise to hit the target (relative to the sight).
John Link, MadSci Physicist
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