Does a bullet fired from a rifle ever get higher
than the barrel assuming that
the barrel is level when fired? I have students that argue that the
bullet rises. I believe that this misconception occurs because they
misunderstand trajectory charts. I have told students that a bullet
is always falling after firing. The reason the bullet is shown higher
at the mid range point is because the barrel is elevated as a result
of the scopes setting. Am I confused about bullet trajectory from a
perfectly horizonal barrel?
No, you are right, they are confused.
No you are correct about a perfectly level and true barrel, the bullet is
always falling. There is a rise due to the design of the rifle and scope
design as you mentioned, but regardless gravity is always working. There is
another experiment to try, or to show your students and may be difficult to
explain without actually drawing it but if you were to take a low velocity
ejector such as a steal ball propelled by a spring through a short barrel
pointing up at a 45 degree angle from the horizon and the barrel was aimed
at a suspended tin can maybe 5 ft higher, and the can was dropped at the
moment the ball was fired it would still hit the can since both objects are
now falling at the same rate. Take a look in a physics book I know this is
a well known example, although it is tricky to perform just because of the
No. You're right. The vertical motion of a bullet can be thought of as
completely independent of its horizontal motion. The vertical motion is
always the same, whether you fire the bullet out of a rifle or drop it
by hand. It just falls, like everything else.
No James, you are not confused. The only way the bullet would rise is if
there is a force to move it. Assuming that there is only gravity - pulling
down- and the force of the gun - pushing horizontally - there would be no
force moving the bullet up. Often the bullet is pictured arcing up and
down portraying (I assume) striking a target at the same level as the
muzzle of the gun...
I believe Newton agrees with you, unless the bullet can "hydroplane" in
the atmosphere. Your explanation of a parallax correction seems reasonable
as a plausible explanation why it may be shown "rising" a bit.
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Update: June 2012