can you reupload the capx please?
The OP hasn't been on here for over 2 years so unfortunately, unless someone still has the .capx (the thread is over 5 years old) then you may be out of luck.
The 'Physics catapult' example that is built in is a basic implementation of Angry Birds. Have you looked at that?
There are also many threads you can find on the forum by a simple search.