Collision and gravity...how?

Hi I need a hand with an effect I’m trying to create.

Basically what I need to produce is a box full of marbles. Imagine the box starting to swell as though more marbles are being added or as though they are growing. Eventually the corner snaps/breaks open and all the marbles start to fall out, filling another box below the break.

Now how would I do that?

I’m guessing I would need to create a collision detection and a gravity engine.

Can someone give me some code to set me off in the right direction or maybe point me towards an FLA I can download?

Thanks for your help.