<font face="Arial, Helvetica, sans-serif">Hi, I need to apply some force to my character but I realized that I can't have the platform and physics behaviur at the same time, what do I do? Thanks</font>
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I made a demo to play with - http://www.scirra.com/arcade/example/9613/platform-force
All it does is simply add or subtract from the platform x/y vector variables when overlapping the green or red boxes.
The red one slowly addes more force the longer you overlap.
You can then create wind/springs or other effects.