Initial motion of a rectangular object being pushed or pulled

Abstract

Techniques are described for determining the location of the initial center of rotation (COR) of a rectangular bar being pushed or pulled. The initial COR is the point about which the bar first rotates when the pushing or pulling force is applied. This point characterizes the initial motion of the bar. Also investigated is how the location of the initial COR varies with the magnitude of the exerted force. The minimum effort criterion is proved to be able to predict the quasi-static centre of rotation. It is found that the initial COR always lies between the quasi-static and the impulsive CORs and that it will move towards the impulsive COR as the magnitude of the applied force increases. It is shown that there exists a point on an object such that, when the force is applied at that point, the object will start to rotate about a known point.