Which of the following is an example of a physical hazard in the workplace?

Ungrounded machinery is a clear example of a physical hazard in the workplace because it poses a direct risk of injury or harm to employees. Physical hazards are typically associated with the physical conditions or objects in an environment that can cause accidents or injuries. Unguarded machinery can lead to entanglement, cuts, crushing injuries, or even fatal accidents if a worker comes into contact with moving parts without proper protection.

Other options may relate to workplace safety but are not classified as physical hazards. Inadequate lighting affects visibility, which could lead to accidents, but it doesn't involve a tangible object that directly harms an individual. Excessive workload pertains more to ergonomic or psychological stressors rather than physical safety. Poor ventilation relates to air quality and comfort rather than a specific physical threat caused by machinery or equipment. Therefore, unguarded machinery is rightly identified as a significant physical hazard.