Consider an area of the open ocean where the mean depth is D . If the ocean floo
ID: 2060740 • Letter: C
Question
Consider an area of the open ocean where the mean depth is D. If the ocean floor in this region is flat, then the ocean surface is flat. But suppose there is a submarine mountain. Then the surface of the ocean would not be flat, because of the gravitational force of the mountain.
(A) Which of the four choices describes the shape of the ocean surface above the submarine mountain?
(B) Approximate the mountain as a sphere of radius h. [Not a very good approximation, but it gives a simple calculation.] Assume the density of the mountain material is 4.0 ×103kg/m3. Calculate the deflection of the ocean surface ( = ) above the mountain.
Hint: The ocean surface is a gravitational equipotential surface.
Data: D = 6030 m; h = 1430 m.
(C) Can the variation of the surface height of the ocean be used for bathymetry, based on satellite observations?
NASA plans to develop this method in the future.
The method is being used today.
The method was tried between 1960 and 1966, but unsuccessful.
The method is not practical.
CHOOSE ONE.
Explanation / Answer
A) The density of water at that depth is greater than the density of the mountain. The mountain being there actualy means there is less mass at that point in the ocean and thus less gravisty and so the answer is C.