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(1) As can be seen from the figure, in the same time, if the distance of an object is longer and longer, the object will accelerate.

(2) As can be seen from the figure, there are five intervals between A and F, so TAF = 5× 0.2s =1s;

sAD=4.5cm，tAD=0.2×3=0.6s，vAD = sAD tAD = 4.5cm 0.6s = 7.5cm/s；

sDF= 12.5cm-4.5cm=8cm，tDF=2×0.2s=0.4s，vDF=sDFtDF=8cm0.4s=20cm/s，

sAF= 12.5cm，vAF = sAFtAF = 12.5cm 1s = 12.5cm/s。

So the answer is: (1) acceleration; (2) 1s； 7.5; 20; 12.5.