BOX2D flash game Applyforce/Apply Impulse?

I am trying to replicate this game for flash using Box2D http://www.physicsgames.net/game/Tric开发者_开发技巧harge.html . I have everything fine, the only problem i am having is when the group of bubbles burst, How do i apply a uniform increase in speed like it does in the game. I have tried ApplyForce, ApplyImpulse but all i get is what looks like an explosion of balls.

It depends on which framework you are using.

One way to accomplish this is to apply a gravity vector that is specific to these objects in the upward direction.

Another way to accomplish this is to apply an elastic joint so that it's a constant acceleration.

I'm assuming you're using http://www.box2dflash.org/docs/2.0.2/manual#The_Joint_Definition. I believe that you may be able to use the mouse joint.