So I got these rocks that I want them to fall from the sky right to the earth but I'm not sure how to get them do that.
Develop games in your browser. Powerful, performant & highly capable.
You could use the bullet-behavior. Set the speed to 0 and the gravity to what you like.
I made a litte example.
https://drive.google.com/file/d/0B5FlDY ... sp=sharing