It was Galileo who first accurately described projectile motion.
He showed that it could be understood by analyzing the horizontal
and vertical components separately. No one had done this prior to Galileo.
This illustration reflects the general opinion before Galileo which followed largely
Aristotelian lines but incorporating a later theory of "impetus" --
which maintained that an object shot from a cannon, for example, followed a
straight line until it "lost its impetus," at which point it fell abruptly
to the ground. |
||Later, simply by more careful observation, as this
illustration from a work by Niccolo Tartaglia shows, it was realized
that projectiles actually follow a curved
path. Yet no one knew what that path was, until Galileo.
There was yet another brilliant insight that led Galileo to his most
astounding conclusion about projectile motion. First of all, he reasoned
that a projectile is not only influenced by one motion,
but by two. The motion that acts vertically is the force of gravity, and
this pulls an object towards the earth at 9.8 meters per second.
But while gravity is pulling the object down, the projectile is also moving forward,
horizontally at the same time. And this horizontal motion is uniform and
constant according to Galileo's principle of inertia. He was indeed able
to show that a projectile is controlled by two independent motions, and
these work together to create a precise mathematical curve. He actually
found that the curve has an exact mathematical shape. A shape that the
Greeks had already studied and called the parabola. The
conclusion that Galileo reached was that the path of any projectile is a parabola.