Final answer:
The question pertains to a component of machinery, where an entire rotating target (disc) is likely mounted on a shaft or stem with a collar or bearings underneath for rotation. The design and function of these components depend on their specific application.
Step-by-step explanation:
The question seems to be describing a mechanical component, specifically a rotating target or disc which is a part of some larger machinery or system. Without additional context, it's difficult to provide an exact answer, but typically, an entire rotating target (disc) would be mounted on a shaft or stem that allows it to rotate, and there could be bearings or a collar underneath to facilitate smooth movement and reduce friction. In engineering, the design of a rotating disc depends on its application. For example, in a wind turbine, the rotating part (the rotor) is attached to a shaft that converts kinetic energy into mechanical energy. In a hard drive, the rotating disc is the platter which is mounted on a spindle that allows for data to be written and read magnetically. Understanding how each component works within its system is critical to ensuring the device operates correctly and safely. Depending on the function, the neck, shaft, or stem would support the disc and connect it to the rest of the assembly, while any additional mechanism underneath such as a bearing would support radial and axial loads.