A Gravity Knife A gravity knife is a knife having blade in its handle; it will open by the gravitational force provided by the person. As we can push or throw the knife then the gravitational force happens and the knife automatically opens. The knife requires the spring or the gravity to open.it can be open and close by one hand, it is the best advantage of it the . The main purpose of the gravity knife is that to help the paratroopers to free themselves from the tricky parachutes. The … [Read more...]