Ergonomics: definition, need and benefits

Direct answer: A, hand and shoulder strain. Ergonomics studies how the worker, equipment and work arrangement fit together. A mouse placed too far away makes the user repeatedly extend the arm, lift or reach the shoulder, and possibly bend the wrist. Even when the keyboard is at a suitable distance, the mouse position can independently create awkward posture and muscular effort. With long or repeated computer use, this extra reaching may cause discomfort or accumulated strain. Option A is correct because it names the body areas most directly affected by repeated reaching. B is not the best answer because the described problem is in the upper limb, not primarily the feet. C is a floor-safety issue and is unrelated to mouse reach. D describes room temperature, not a posture or equipment-placement problem. Memory cue: every frequently used tool should be close enough to use without stretching.

Direct answer: A, ignoring real user diversity. Ergonomic design must consider the range of people who will use a product, not just one average measurement. A desk fixed at the average height may be too high for a shorter worker and too low for a taller worker, forcing awkward shoulder, elbow, wrist or back positions. The practical solution may include adjustable furniture or a design based on appropriate user-size ranges. A is correct because the error is treating a diverse group as if everyone had the same body dimensions. B is irrelevant: colour does not explain posture-related pain. C does not identify a furniture-fit problem. D concerns naming, not physical comfort or safety. Memory cue: average is a statistic, not automatically a suitable setting for every person.

Direct answer: A, it helps identify causes and risky steps. A work process is made of separate actions, such as reaching, lifting, pressing, turning or repeating a movement. If discomfort becomes stronger during one particular action, that timing gives a useful clue about the exposure causing it. The observer can then examine posture, force, duration, repetition and equipment at that step and suggest a safer change. A is correct because comparing symptoms with the sequence of work supports cause-finding rather than guesswork. B is incomplete and misleading: symptoms are experienced by a person, but their pattern may still be related to work conditions. C is the opposite of ergonomic analysis. D is false because the purpose is to improve work, not automatically stop it. Memory cue: find when the pain rises, then inspect what the worker is doing at that moment.

Ergonomics evaluates the fit between people, tasks, tools, and the workplace. A faster output rate does not prove that the design is healthy, because workers may be using awkward postures, excessive force, repetitive motions, or poorly placed equipment. Thus A is correct: hidden physical strain and other fatigue indicators should be assessed. B wrongly treats speed as the only outcome, while C and D do not provide valid evaluation methods.

Direct answer: A, twisted sitting posture and back strain. Good computer ergonomics requires the chair and the worker’s trunk to face the screen so that the head, neck and spine can remain near a comfortable alignment. If the chair is turned sideways, the person may repeatedly rotate the neck, shoulders or trunk to look forward. Holding or repeating this twisted position can create muscular fatigue and discomfort, especially in the back and neck. A is correct because it identifies the likely postural problem caused by the mismatch between chair direction and screen position. B is wrong: a sideways chair does not improve screen use. C is the opposite of the likely effect and is unsupported. D is wrong because the misalignment is a real ergonomic risk even if pain has not appeared yet. Memory cue: align the chair, body and screen in one forward direction.

Direct answer: A, repeated light movements can accumulate strain. Ergonomic risk depends on more than the weight or force of one movement. When the same action is performed frequently, the same muscles and joints may receive little recovery between repetitions. Over time, fatigue or discomfort can build, particularly if posture is fixed, the pace is high or rest breaks are insufficient. A is correct because it recognises cumulative exposure: a small demand repeated many times may become a substantial total demand. B is wrong because light does not mean risk-free. C denies the known importance of repetition in work analysis. D is wrong because suitable pauses and variation can help recovery; the exact need depends on the task and worker. Memory cue: assess force and frequency together—small loads can still matter when repeated for long periods.

Direct answer: A, to understand the force, time, attention and posture demanded by the task. Work demand analysis breaks a task into what the worker must physically and mentally do. It can include the force required, the duration and pace, repeated actions, visual or mental attention, reach distance and the posture that must be held. Designers can then compare these demands with human abilities and limitations and improve tools, layout, work methods or rest arrangements. A is correct because it covers the main kinds of demand that affect safety, comfort and performance. B is too narrow: preference may matter, but it is not the purpose of demand analysis. C and D have no connection with ergonomic assessment. Memory cue: first understand the task’s demands, then make the task fit the worker more safely.