Combined Motion of Rotation and Translation

INTRODUCTION

We have already discussed in chapter 17 linear motion or motion of translation. And we have also discussed in the last chapter motion of rotation. But sometimes a body has, simultaneously, a motion of rotation as well as translation such as wheel of a car, a sphere rolling (without slipping) on the ground etc. A little consideration will show, that such a motion will have the combined effect of rotation as well as translation. Now in this chapter, we shall discuss the combined motion of rotation and translation.

MOTION OF A RIGID LINK

Consider a rigid link AB, which moves from its initial position AB to its final position A1B1. It will be interesting to know that the link neither has, wholly a motion of translation nor wholly

rotational, but a combination of the two. But the point B moves faster than the point A as shown in Fig. 22.1. (a).

INSTANTANEOUS CENTRE