Examkin

Question

Difficulty: HardLatitude, Longitude, and Time Calculations

A solar observation station located at longitude 23∘W23^\circ\text{W} records local solar noon (12:00 PM12:00\text{ PM}) at a specific instant. At that exact moment, a research vessel at sea notes its local solar time as 7:16 PM7:16\text{ PM} (19:1619:16) on the same day. What is the longitude of the research vessel in degrees East?

Answer: 86 degrees East

Answer

The research vessel is located at 86∘E86^\circ\text{E}.
The time difference between 12:00 PM and 7:16 PM is 7 hours and 16 minutes (436 minutes). Since 4 minutes correspond to 1° of longitude, the angular difference is 436 ÷ 4 = 109°. Because the vessel's solar time is later than the station's time, the vessel lies to the East. Moving 109° East from 23°W requires 23° to reach the 0° Greenwich Meridian and an additional 86° into the Eastern Hemisphere, placing the vessel at 86°E.

Step-by-Step Solution

1
Determine the time difference between the solar observation station and the research vessel.
Time difference = 19:16 - 12:00 = 7 hours and 16 minutes = 436 minutes.
Difference in local solar time corresponds to longitudinal separation.
2
Convert the time difference into longitudinal degrees using the rate of Earth's rotation (1∘=4 minutes1^\circ = 4\text{ minutes}).
Longitudinal difference = 436 ÷ 4 = 109°.
The Earth rotates 360° in 24 hours, which equals 1° for every 4 minutes of time difference.
3
Determine the direction of the vessel relative to the station.
The vessel is East of the station.
Local solar time at the vessel (7:16 PM) is ahead of the station (12:00 PM), meaning the vessel lies further East.
4
Calculate the absolute longitude in the Eastern Hemisphere.
Vessel longitude = 109° - 23° = 86°E.
Traversing 109° East starting from 23°W uses 23° to reach the Greenwich Meridian (0°) and the remaining 86° extends into the Eastern Hemisphere.

Key Concept

Calculating longitude from local solar time difference across meridians
Rate this question

Topics

Latitude, Longitude, and Time Calculations

More questions from this topic