A door is unlocked by inserting and turning the key and opened by turning the handle. The options show the directions of turning the key and the handle. Which of the four options is ergonomically appropriate for the majority of users?
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For ergonomics questions, think about common user expectations and conventions (e.g., "righty-tighty, lefty-loosey"). Also consider the natural movements of the human body, such as the wrist and arm. Actions that align with these are generally more ergonomic.
Step 1: Understanding the Concept:
Ergonomics is the science of designing products to be efficient and comfortable for human use. For a door lock and handle, this means the required motions should feel natural, intuitive, and require minimal strain. We need to evaluate the combination of key-turning and handle-turning motions.
Step 2: Detailed Explanation:
Let's analyze the common ergonomic principles for these actions, assuming a majority of right-handed users.
Handle Motion: The downward rotation of a handle to unlatch a door is a universally accepted standard. It works with the natural motion of the hand and wrist. All four options (A, B, C, D) show a downward handle motion, which is ergonomically sound.
Key Motion: The direction for locking/unlocking can vary. However, a common convention is "clockwise to tighten/lock" and "counter-clockwise to loosen/unlock". Let's assume we are unlocking the door. A counter-clockwise turn would be expected.
Let's evaluate the options based on the combination of motions:
Option A: Clockwise key turn, downward handle turn.
Option B: Clockwise key turn, upward handle turn. The upward handle turn is highly un-ergonomic.
Option C: Counter-clockwise key turn, downward handle turn. This combines the standard downward handle motion with an intuitive counter-clockwise "unlocking" motion for the key. The two sequential motions (turn key away, pull handle down) flow well.
Option D: Counter-clockwise key turn, upward handle turn. The upward handle turn is un-ergonomic.
Comparing A and C, both are plausible. However, the sequence in C (turning the key away from the handle's pivot before moving the handle) can be considered slightly more fluid. Given that "counter-clockwise to unlock" is a strong convention, C is arguably the most appropriate design. The Answer Key states "FULL MARKS", which acknowledges the potential ambiguity, as conventions can differ.
Step 3: Final Answer:
Options B and D are ergonomically poor due to the upward handle motion. Between A and C, option C represents a very common and intuitive combination: counter-clockwise to unlock, and down to open. This makes it a highly appropriate choice.
