Let us consider a link AB which takes the position A’B’ after a short interval of time. Here the link has combined motion of translation and rotation.
Fig. 4.2 (a) shows that the total motion can be broken up into first translation from AB to A’B* and then rotation from A’B* to A’B’.
Fig. 4.2 (b) shows that the total motion can also be broken up into first rotation from AB to AB* and then translation from AB* to A’B’.