Crossbows are a very a cool weapon. They use tension and potential energy to shoot arrows. You first pull the string back, which requires a large amount of force, lock it in place with the spring system and then pull the trigger which drops the lock and sends the string and arrow launching forward at a high velocity. When the string is pulled back and locked in place, potential energy is built up. The more potential energy that is built up, the faster and stronger the arrow will launch once the trigger is pulled. Crossbows are fairly simple, yet very deadly.