Can you be killed by a falling bullet?
It's always dangerous when somebody fires a gun into the air, but
it's not always deadly because the bullet falls at only about one tenth
of it's muzzle velocity.
A slow falling bullet may not have enough velocity to penetrate you
deeply, since a falling bullet hits terminal velocity at only about 300
feet per second, about 200 miles per hour.
Remember, gravity continuously pulls a bullet down as a direction of
the air time of a bullet.
But what about the increasing
velocity of a falling bullet?
In a vacuum, the increasing force
of gravity would continue to accelerate a falling bullet until it
asymptotically approached the speed of light. (The “speed of
sound” only relates in an environment with air).
environment with both air and gravity, a falling bullet will only
continue to accelerate until the air resistance equalized with the pull
of gravity, an effect knows as “terminal velocity”.
Without air resistance a 30 caliber bullet would start at 3,000 fps and
rise to 100,000 feet, taking 90 seconds to achieve peak altitude, and
another 90 seconds to fall back to earth.
For example, in cats,
studies have been done of the terminal velocity of cats falling from
apartments in Manhattan that show cats surviving 20 story falls from
apartment windows! On average, the cats fell 5.5 stories, yet 90
percent survived their falls because of feline terminal velocity which
is about 60 MPH.
A human skydiver has a terminal velocity of
about 120 MPH.
But a bullet is much more compact than a cat, and
eventually, the air resistance will stop the acceleration.
States Army tests in 1920 showed that a 30 caliber bullet hit terminal
velocity at about 300 fps, or about 205 miles per hour.
In sum, a
falling bullet has only one-tenth of its initial muzzle velocity.