Question

At your local apparent noon, or local meridian, your chronometer indicates that it is 7:40 am in Greenwich. What is your longitude?

a) Interpreting time differences to determine geographical locations.
b) Calculating time zone variations across longitudes.
c) Using Greenwich Mean Time (GMT) to find local time.
d) Applying principles of navigation to determine longitude.

Answer 1

The longitude of the location is 65 degrees west, based on the time difference of 4 hours and 20 minutes between the local apparent noon and Greenwich Mean Time (GMT).

Step-by-step explanation:

When your local apparent noon or local meridian occurs, and your chronometer reads 7:40 am in Greenwich, you can determine your longitude by calculating the time difference between your local time and Greenwich Mean Time (GMT). Since local apparent noon is equivalent to 12:00 pm, there is a 4 hour and 20 minute difference between your location and Greenwich.

Each hour difference represents 15 degrees of longitude, as Earth rotates 15 degrees per hour. For the 4 hours, you have 4 x 15 degrees, which equals 60 degrees, and for the remaining 20 minutes, you take (20/60) x 15 degrees, which equals 5 degrees. Therefore, your longitude is 65 degrees west because Greenwich is ahead of your local time.