CES Industrial & Manual Handling Ergonomics 2 — Questions and Answers
Question 1: What does the 'frequency multiplier' in the NIOSH Lifting Equation adjust for?
- The number of lifts per minute and duration of the lifting task (Correct answer)
- The worker's lifting frequency preference
- The frequency of supervisor observations
- The number of workers performing the task
Correct answer: The number of lifts per minute and duration of the lifting task
The frequency multiplier reduces the RWL as lifting frequency and task duration increase, accounting for the cumulative metabolic and biomechanical fatigue associated with repeated lifts.
Question 2: Which ergonomic hazard is most associated with using a vibrating power tool for extended periods?
- Hand-arm vibration syndrome (HAVS) causing vascular and neurological damage (Correct answer)
- Contact stress from tool handle pressure only
- Wrist tendinitis from grip force only
- Shoulder impingement from tool weight
Correct answer: Hand-arm vibration syndrome (HAVS) causing vascular and neurological damage
Prolonged exposure to vibrating hand tools can cause HAVS, characterized by Raynaud's phenomenon (white finger), peripheral neuropathy, and musculoskeletal damage in the hands and arms.
Question 3: In assembly line ergonomics, what does 'cycle time' refer to and why is it important?
- The time to complete one work cycle, which determines repetition rate and musculoskeletal demand (Correct answer)
- The time between equipment maintenance intervals
- The shift duration for assembly workers
- The time needed to train a new worker on the task
Correct answer: The time to complete one work cycle, which determines repetition rate and musculoskeletal demand
Cycle time determines how frequently a worker repeats specific motions; short cycle times mean high repetition rates, increasing cumulative tendon and muscle loading and MSD risk.
Question 4: What is the primary ergonomic concern with a precision grip versus a power grip in industrial tasks?
- Precision grip requires much higher relative muscle force and causes greater tendon loading for equivalent tasks (Correct answer)
- Power grip is always more hazardous than precision grip
- Precision grip causes direct joint injury
- The two grips have identical biomechanical loading
Correct answer: Precision grip requires much higher relative muscle force and causes greater tendon loading for equivalent tasks
Precision grip uses a smaller contact area and fewer muscles, requiring proportionally greater effort to achieve the same force as power grip, resulting in higher muscle and tendon loading.
Question 5: What is the ergonomic benefit of anti-fatigue mats for workers who stand for prolonged periods?
- They reduce lower limb fatigue by promoting subtle weight-shifting micro-movements (Correct answer)
- They eliminate all standing-related injury risk
- They are primarily a slip prevention measure
- They replace the need for proper footwear selection
Correct answer: They reduce lower limb fatigue by promoting subtle weight-shifting micro-movements
Anti-fatigue mats create a slightly unstable surface that encourages continuous micro-movements of leg muscles, improving circulation and reducing static muscle loading from prolonged standing.
Question 6: Which characteristic of industrial workstations primarily determines whether a task should be performed seated or standing?
- Combination of task force requirements, precision demands, and required reach zones (Correct answer)
- Worker preference exclusively
- Industry tradition and historical practice
- OSHA mandate for specific job categories
Correct answer: Combination of task force requirements, precision demands, and required reach zones
Tasks requiring high force benefit from standing while precision tasks often benefit from sitting, and reach zone analysis determines which posture is most ergonomically appropriate.
CES Industrial & Manual Handling Ergonomics 2
What does the 'frequency multiplier' in the NIOSH Lifting Equation adjust for?