Caduta verticale di un grave = caso particolare di moto di un grave.
http://commons.wikimedia.org/wiki/File:Falling_ball.jpg
An initially-stationary object which is allowed to fall freely under gravity
drops a distance which is proportional to the square of the elapsed time. This
image, spanning half a second, was captured with a stroboscopic flash at 20
flashes per second. During the first 1/20th of a second the ball drops one unit
of distance (here, a unit is about 12 mm); by 2/20ths it has dropped at total of
4 units; by 3/20ths, 9 units and so on.
To take the picture, the ball - about the size of a tennis ball - was suspended
by a short length of black thread and was released as the shutter was opened and
the flash triggered. The shutter remained open for the whole of the half-second
period, during which time the flash fired multiple times to capture the ball at
1/20 second intervals.
http://commons.wikimedia.org/wiki/File:Falling_ball_original_plus_text.jpg
