The trebuchet was a very popular weapon used in the medieval times. They have very intricate designs even though they look quite simple. They have a swinging arm to projectile the thing they wish to throw. These weapons were used to throw heavy loads. There is a sling that unhinges when it hits a certain height. As the arm rotates, the things in the thing experience centripetal acceleration which causes it to move out. The initial release position is such that the beam on the counterweight side makes an angle of 45° with the vertical. There is a lot of math required in finding the trajectory of the arms through. The trebuchet reached Europe during the early Middle Ages, or Dark Ages, in 500 AD and was used extensively by the French.