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NAUTICAL KNOT LATITUDE AND LONGITITUDE

   

       On land we measure distance in kilometers and miles.  For a ship sailing in ocean for months and for a jet plane flying from one continent to another, these measurements will not be suitable because earth is spherical and curved.  That is where the 'nautical mile' comes in.  Let us understand the concept.
     The earth roughly takes 365 days to go round the sun once.  Hence mathematicians divided a circle into 360 equal parts and defined the total angle of circle as 360 degrees.
     To improve accuracy,  one degree is sub-divided into 60 minutes and a minute is further segmented into 60 seconds.  The same technique is followed in the clocks since the clock handles move in circles.
     We have drawn imaginary vertical and horizontal lines on the earth called latitude and longitude.  They are based on angle measured in degrees.  They are used by GPS to pinpoint a location on the surface of the earth.

     Nautical mile is the distance suspended by one minute (1/60 of a degree) angle of latitude.   It is equal to 1852 meters or 1.151 land mile or 6076 foot.  We know they are mainly used in air and sea.  They help easy reading of charts
since the location given by latitude and longitude and the distance can be easily co-related.
     If a ship moves  one nautical mile per hour the speed of the ship is said to be one-knot.  Before the advent of technology sailors measured speed of a boat using the rope having knots.  Hence the name 'knot'
     Note:  Today, we measure the angle in radian in physics.  A circle is said to have total angle of 2pi radian or 2* 3.14 radian or 6.28 ....radian.  One radian = 57.296 degrees.
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