Suppose a link AB goes through a motion and takes a new position as A’B’ after a specific period of time. Considering the motion of the link, it takes combined motion of rotation and translation which is shown in Fig. 4.1

If the total motion of the link AB is broken into two. First it goes for translation motion to reach A’B* and second it goes for rotation to reach A’B’ as shown in Fig. 4.2 (a)

Suppose the total motion of the link AB is again broken into two. But here first it goes for rotation to reach AB* and second it goes for translation to reach A’B’ as shown in Fig. 4.2 (b)