Fundamentals of Surveying (FS) Practice Exam

What do meridians, or lines of longitude, measure in reference to the prime meridian?

1. Arc distance northerly and southerly

2. Arc distance east and west

3. Arc distance from the equator

4. Arc distance from the poles

The correct answer is: Arc distance east and west

Meridians, or lines of longitude, are used to measure arc distances east and west of the prime meridian, which is situated at 0 degrees longitude. The prime meridian serves as the reference point for determining longitude, defining the eastern and western hemispheres. As you move east or west away from the prime meridian, the degrees of longitude are marked incrementally, reaching up to 180 degrees in both directions. This angular measure is crucial for navigation and mapping, allowing for the precise identification of locations on the Earth's surface relative to the established baseline of the prime meridian. The other choices refer to different types of measurements: northerly and southerly distances are captured by lines of latitude, which measure positions relative to the equator. Arc distance from the equator is also latitude-related, while arc distance from the poles pertains to another concept in geography and does not relate to longitude measurement.