RPLS Mathematics and Geodesy 2 — Questions and Answers
Question 1: A geodetic survey uses the GRS80 ellipsoid. What is the semi-major axis (a) of this ellipsoid?
- 6,378,137.0 m (Correct answer)
- 6,356,752.3 m
- 6,371,000.0 m
- 6,378,206.4 m
Correct answer: 6,378,137.0 m
The GRS80 ellipsoid has a semi-major axis of 6,378,137.0 m, which is also used by WGS84.
Question 2: In a traverse computation, the angular closure error is distributed equally among all angles. This method is called:
- Compass rule adjustment
- Bowditch adjustment
- Equal angular distribution (Correct answer)
- Least squares adjustment
Correct answer: Equal angular distribution
Equal angular distribution divides the total angular closure error equally among all measured angles in the traverse.
Question 3: What is the geodetic azimuth from Point A to Point B if the back-azimuth from B to A is 47°30'15"?
- 227°30'15" (Correct answer)
- 137°30'15"
- 317°30'15"
- 47°30'15"
Correct answer: 227°30'15"
The forward azimuth is found by adding or subtracting 180° from the back-azimuth: 47°30'15" + 180° = 227°30'15".
Question 4: The term 'geoid undulation' (N) refers to the separation between which two surfaces?
- The geoid and the ellipsoid (Correct answer)
- The ellipsoid and mean sea level
- The topographic surface and geoid
- The datum and the geoid
Correct answer: The geoid and the ellipsoid
Geoid undulation N is the vertical distance between the geoid and the reference ellipsoid at any given point.
Question 5: A surveyor measures a horizontal angle by repetition six times and obtains a total accumulated reading of 521°12'36". What is the mean angle?
- 86°52'06" (Correct answer)
- 87°52'06"
- 86°52'26"
- 87°22'06"
Correct answer: 86°52'06"
Dividing 521°12'36" by 6 gives 86°52'06" as the mean measured angle.
Question 6: On a plane survey, the latitude of a course is defined as:
- The northing or southing component of a course (Correct answer)
- The easting or westing component of a course
- The horizontal distance of a course
- The vertical angle of a course
Correct answer: The northing or southing component of a course
Latitude is the orthogonal projection of a course onto the north-south meridian, yielding the northing (+) or southing (−) component.
Question 7: Which coordinate system is used as the foundation for the North American Datum of 1983 (NAD83)?
- GRS80 ellipsoid (Correct answer)
- Clarke 1866 ellipsoid
- WGS72 ellipsoid
- Bessel ellipsoid
Correct answer: GRS80 ellipsoid
NAD83 is referenced to the GRS80 ellipsoid, which is virtually identical to WGS84 in its defining parameters.
RPLS Mathematics and Geodesy 2
A geodetic survey uses the GRS80 ellipsoid.
What is the semi-major axis (a) of this ellipsoid?