Final answer:
Reciprocating motions can be hazardous as they can lead to workers being struck by or caught between moving and stationary parts, posing significant risks of injury.
Step-by-step explanation:
Reciprocating motions may be hazardous because, during the back and forth or up and down motion, a worker may be struck by or caught between a moving and a stationary part. This type of motion uses the rotation of a motor to produce linear action, as seen in tools like reciprocating saws. Risk is inherent in such motions because the worker can be injured by the moving parts or by contact with stationary objects. Furthermore, long-term exposure to such motions can lead to repetitive stress injuries, contributing to other health issues like back problems, swollen feet, and hearing loss due to constant noise.