In a four-bar linkage, what is the mechanism formed when one link is fixed referred to?

• A. Inversion
• B. Rotation
• C. Reciprocation
• D. Transformation

Answer: (A)

In a four-bar linkage, when one link is fixed, the mechanism is referred to as "inversion." Inversion in this context means that fixing one of the links changes the function and motion of the mechanism. In a four-bar linkage, there are four links (the fixed link, two moving links, and the coupler) and the way they are connected allows various types of movement depending on which link is fixed.

When one link is immobilized, the remaining three links can still move relative to one another, creating a specific motion path. Each configuration with a different fixed link leads to a different kind of motion or output from the mechanism, which is the essence of linkage inversion. This property is fundamental to the design and analysis of mechanical systems, as it allows engineers to convert inputs into desired outputs effectively.

The other options represent different concepts in kinematics and mechanisms. For example, rotation refers to the circular movement of links but doesn't define the overall transformation of the mechanism based on fixed links. Reciprocation describes a back-and-forth linear movement, typically not exclusive to a four-bar linkage. Transformation might refer to how motion is changed, but it doesn't explicitly capture the fixed link aspect in the context of a four-bar linkage system.