A walks 10 m forward (assume North), then 10 m to the right (East). Then, turning left each time, he walks 5 m, 15 m, and 15 m. How far is he from the starting point now?
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A5 meters
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B10 meters
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C20 meters
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D23 meters
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ENone of these
Answer
Correct Answer: 5 meters
Explanation
Introduction / Context:We combine relative turns with fixed step lengths. Start with a notional facing (North), then interpret “right” and successive “left” turns relative to that orientation while accumulating coordinates.
Given Data / Assumptions:
- Forward 10 (North): (0,10).
- Right 10 (East): (10,10).
- Left → face North, go 5 → (10,15).
- Left → face West, go 15 → (−5,15).
- Left → face South, go 15 → (−5,0).
Concept / Approach:Use consistent left/right relative to current heading, not absolute axes. Then apply distance formula to final coordinates.
Step-by-Step Solution:End position: (−5, 0).Distance from origin = sqrt((−5)^2 + 0^2) = 5 m.
Verification / Alternative check:Vertical components end at y = 0; net horizontal is 5 m West, hence magnitude 5 m.
Why Other Options Are Wrong:10/20/23 m do not match the computed displacement.
Common Pitfalls:Losing track of the third and fourth turns, or treating “left” as absolute West.
Final Answer:5 meters