Hi,im making some project with tank and i was wondering how to make that shoot force,u know when the tank fires it shake if u understand me 
So you’re looking for a Camera Shake effect?
Few threads on information regarding camera effects:
http://forum.unity3d.com/threads/63248-Camera-Shake-Using-Random-Rotation
http://forum.unity3d.com/threads/3194-How-to-shake-our-camera
http://forum.unity3d.com/threads/2872-quot-Window-Shake-quot?p=20852
http://forum.unity3d.com/threads/60645-Camera-shake
Did a quick search for camera shake and those popped up. There was quite a bit more but hopefully some of those can help you 
Regards,
Rob
thank you it was helpful