What is the purpose of a cam in machines?

The purpose of a cam in machines is primarily to convert rotational motion into linear motion, which is accurately represented by the chosen answer. Cams are specially designed mechanical wheels or disks that have a specific profile or shape. As the cam rotates, its shape causes a sliding element, like a follower, to move in a linear path. This movement can be used to open or close valves, operate machine components, and perform other tasks that require precise linear motion corresponding to the rotational input.

The significance of this functionality is prominent in many applications such as in engines where camshafts control the timing of valve openings and closings, ensuring optimal engine performance. By understanding this mechanism, you can appreciate how linear motion is effectively derived from circular motion, harnessing the cam's profiled contour to achieve desired mechanical outcomes.