Q. A kinematic chain is known as a mechanism when

A kinematic chain is a combination of links connected in a specific order, allowing relative motion between them. When one of the links in a kinematic chain is fixed or stationary, it is termed a mechanism. This fixed link provides a frame of reference against which the motions of other links are observed. The fixed link is often referred to as the "ground" or "frame" link, and it serves as a foundation for the movement and analysis of the remaining links in the kinematic chain.