This is a pretty intensive programming project. Be aware that in 8-ball, there are 16 balls total (15 colored + cue ball), so in every frame, you have to check (15+14+13+12+11+10+9+8+7+6+5+4+3+2+1) = 120 different collisions. That's a significant amount of processing time for Scratch.
Offline
This is not an easy game to simulate.
Here is something to get you started: http://scratch.mit.edu/projects/realSAB/1131095
Offline
You can also look at http://scratch.mit.edu/projects/amcerbu/1652180.
Offline