I've made a character, and used the bone tool to make it move in runtime.
This works fine, but now I want to add gravity/physics, so I can throw my character and it lands on the ground like a real ragdoll. How do I do this in actionscript 3 ? And is it possible to do this within the fla (no class file).
Thanks in advanced!
I'm not a bones tool expert but it's really really really unlikely.
You can do it without the class file, coding only on the timeline, but not without code, which is probably what you asked.
http://box2dflash.sourceforge.net/
This is FlashBox2D, physics engine for flash based on a C++ engine by Erin Cato. Since you asked whether it can be done without the class file, you should probably pass over over this particular engine since C++ programing is very complicated because of the way C++ programing "pros" force you to micromanage every minute detail of the program for ultimate in memory management. Just creating a basic circle shaped body is on the order of 10-15 lines of code. Creating the world is close to that as well. Luckily, there is copy paste.
I don't know if other engines are less verbose (they should be), but I suggest you check them out as well, in case one of those suits you more.
Nice thing is that you can just reuse their example code for your needs if you can get your head around it.
http://www.flashrealtime.com/flash-game-library-engine-list/#Physics
Have fun.