Question

Which statement correctly distinguishes the geoid from an ellipsoid?

• A. Ellipsoid represents mean sea level, geoid is a mathematical surface
• B. Geoid represents mean sea level, ellipsoid is a mathematical approximation of Earth's shape
• C. Both are exactly the same
• D. Ellipsoid is used only in oceans

Hint:

Remember: \[ \boxed{ \begin{aligned} \text{Geoid} &\rightarrow \text{Physical Earth (MSL)} \text{Ellipsoid} &\rightarrow \text{Reference mathematical surface} \end{aligned} } \]

Answer 1

The Correct Option is B

Concept: The geoid and ellipsoid are two important reference surfaces used in geodesy.

Step 1: Understand the geoid. The geoid is an irregular surface that closely corresponds to the Earth's mean sea level under the influence of gravity.

Step 2: Understand the ellipsoid. The ellipsoid is a smooth mathematical surface used for mapping, surveying, and GPS calculations. Thus, \[ \boxed{ \begin{aligned} \text{Geoid} &\rightarrow \text{Mean Sea Level} \text{Ellipsoid} &\rightarrow \text{Mathematical approximation of Earth} \end{aligned} } \] Therefore, the correct option is \[ \boxed{(B).} \]