I have modified the code according to what you would like to do:
You can change the slider to modify mass ratio between different balls.
The initial mass ratio are: m2:m1=5./3.; m3:m2=2:1, m4:m3=3:1
Just hit [b]play [/b]and you will find out. You can change it to other ratios.
If initial mass ratio are 1:2:10:30 (m21=2, m32=5, m43=3) :only the last one will be stopped.

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