Catapult vs zombies

Zombies start attacking people, you have no choice as to invent a weapon against them is capable not let them to you! When you finished it, you now have what defense and you're ready for this fight! Tighten as much as possible and hold special rubber, and then a huge stone will fly right into them and will destroy all in its path who will! Proceed very quickly and accurately, and then you will be saved!