Explain how readings on these gravity instruments indicate deposits of minerals?

[pokeefer]

Homework Statement

(4 marks)

Instruments that measure the force of the Earth's gravity with great accuracy are carried in airplanes over mineral-bearing landscapes. Explain how readings on the instruments indicate when there is a deposit of minerals or oil below the plane.

Homework Equations

N/A

The Attempt at a Solution

I know that the force of gravity is a centripetal force that makes it go towards the centre of the Earth but I have no idea how you would use a gravitational instrument to find deposits of minerals or oil.

Thanks.

 

[D H]

I know that the force of gravity is a centripetal force that makes it go towards the centre of the earth

The gravitational force vector in general does not point toward the center of the Earth.

but I have no idea how you would use a gravitational instrument to find deposits of minerals or oil.

What's going to happen if the plane flies over something buried but near the surface that is much more or much less dense than average?