Due to the curvature of the earth.

1 knot. = 1.15 mile/hour, or 1 nautical mile = 1.15 linear miles.

You can ballpark remember it as 2000 yards, which is also known as a RADAR (Nautical) mile. The difference from 6080 feet and 6000 ft (2000 yd) is about 1%

1 nautical mile = 6,080 feet, = (6,080/5,280) = 1.1515(r) miles (per hour).

1 Knot = 1.15077845 Miles Per Hour

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