Because the ball was released from rest, and because it was accelerating at a constant rate, its displacement varied with time according to the formula s=1/2 a t2.
By noting the positions of the golf ball at equal time intervals, we confirm that the displacement was indeed increasing quadratically with time.
This video also tells me that my eyes are not very good at judging velocity, and totally hopeless at judging acceleration. Haha.
xmDemo 
Reblogged this on lessonidea and commented:
ta ta ta