What is a rigid piece that serves to transmit force between two pieces or control motion?

The term that best describes a rigid piece that transmits force between two components or controls motion is "link." In mechanical systems, a link serves as a structural element that connects different parts, allowing for the transfer of forces and facilitating movement. Links are fundamental components in mechanisms, often providing support and helping to maintain the spatial relationships between moving parts.

For example, in a linkage system, links can control the motion of other parts, enabling transformations of motion, such as converting rotary motion into linear motion or vice versa. This ability to transmit forces while providing structural integrity is essential in many mechanical applications, making links a vital part of machine design.

In contrast, the other options refer to components that have specific roles within mechanical systems but do not encapsulate the broad definition of a link. A follower, for example, typically interacts with a cam and follows its profile to convert rotational motion into linear motion, while a crank is specifically designed to convert rotary motion into linear motion in conjunction with links. Cam motion is a specific type of motion governed by the profile of a cam and the follower's movements. Therefore, while these components play important roles, they do not define the generalized function of a rigid piece that transmits force and controls motion as effectively as a link