At 2021 your position is LAT 41°09.7'N, LONG 72°59.8'W. At 2057 your position is LAT 41°00.5'N, LONG 72°49.5'W. What are your true course and speed made good?
• How to calculate a course and distance between two latitude/longitude positions using a plotting sheet or chart • Converting elapsed time in minutes to hours to use in the speed formula • The relationship: Speed = Distance / Time and using true course (from north, clockwise) based on your plotted track
• First, sketch or plot both positions and draw the line of travel. In which general compass quadrant (NE, SE, SW, NW) are you moving? Use that to quickly eliminate obviously wrong course answers. • Measure the track angle from true north through the second position. Is the angle closer to 140–145° or 316–320° based on the direction you just sketched? • Compute the distance run in nautical miles between the two positions, then divide by the elapsed time in hours. Which answer choice’s speed is closest to that value?
• Confirm the time difference between 2021 and 2057 in decimal hours before using the speed formula. • Carefully measure the difference in latitude and longitude, and remember that 1 minute of latitude = 1 nautical mile. • When reading the course, make sure it is a true course (referenced to true north) and expressed as a three-digit bearing (000°–359°).
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