GATE CE 2017 Set 2 — Question 55
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Geomatics Engineering → Levelling → Curvature & Refraction Correction
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Question
An observer standing on the deck of a ship just sees the top of a lighthouse. The top of the lighthouse is 40 m above the sea level and the height of the observer's eye is 5 m above the sea level. The distance (in km, up to one decimal place) of the observer from the lighthouse is ___________
Correct answer
32.5 to 33.5
Solution
The distance to the horizon (in km) for a height (in m) considering the combined effect of curvature and refraction is given by the formula:Given:
Height of the observer's eye, m
Height of the lighthouse, mThe total distance between the observer and the lighthouse is the sum of their individual distances to the horizon:Rounding to one decimal place, the distance is 33.0 km.
Height of the observer's eye, m
Height of the lighthouse, mThe total distance between the observer and the lighthouse is the sum of their individual distances to the horizon:Rounding to one decimal place, the distance is 33.0 km.
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