How do I create Falling rock better?

Hi,

look at to

s3.picofile.com/file/8208290776/physic.capx.html

i want to create falling rocks better, but i do not know, also the rocks in capx, do not stop on the ground(the green sprite)

please help and edit the capx.

thank you

just add physics to the ground - and make it immovable.

1- my ground has several sprite,

2- i want to create falling rocks better and real !

any help?!