"Stroboscopic photography" is a common research method to study the motion of objects. In the darkroom, the shutter of the camera is always open and the stroboscope is timed.

(1) As can be seen from the figure, the distance of the ball at the same time is getting bigger and bigger, and the distance at the same time is not equal, so the ball moves in a variable speed straight line.

(2) As can be seen from the figure, the relationship between the ball movement time and the corresponding distance is: t 1=0.04s, s 1=0.8cm, t2=0.08s, s 1=3.2cm, t3=0. 12s. S5= 19.6cm, t6=0.24s, s6=28.4cm The falling distance s of the ball is proportional to the square of the corresponding time t, and st2=5m/s2. Therefore, the distance the ball falls from rest is proportional to the square of time.

So the answer is: (1) variable speed; (2) The distance the ball falls from rest is proportional to the square of time.