Question
Download Solution PDFThe captain in a vessel 0.016 km above the sea level observes a 0.144 km tall lighthouse on a port just above the horizon. The distance of the vessel from the port, considering both curvature of the Earth and refraction, is _________.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept
Distance of Visible Horizon
D = 3.855(√H1+√H2)
If the observer has a height of H1 (m) and the object has a height of H2 (m)
the distance between horizons will be D which is in km.
Given
H1 = 144m
H2 = 16m
Calculations
\(D = 3.855 (\sqrt{H1} + \sqrt{H2} )\)
\(D = 3.855 (\sqrt{144} + \sqrt{16} )\)
D = 61.68 Km(Ans)
Additional Information Combined correction is the combined effect of curvature correction and refraction correction.
Curvature correction (CC) = - 0.0785 × D2,
Refraction correction (CR) = + 1/7 × Cc = + 0.0112 x D2
Combined Correction (C) = - 0.0673 x D2
Note:
Combined Correction (C) & Curvature correction (CC) are always negetive(-ve)
Refraction correction (CR) is always positive(+ve)
Confusion Points The above correction's sign(-ve) has to be applied only in staff readings not on Reduced Levels.
Last updated on May 28, 2025
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