I'm taking an introductory geology class and am having big trouble with the math questions, as it's been many many years since I last took math classes.(adsbygoogle = window.adsbygoogle || []).push({});

I am to use Archimedes Principle to calculate the thickness of continental crust beneath a certain coastal geographical point (at sea level and not accounting for post glacial rebound effects).

Data given:

Water depth to the abyssal plain: 5000m

Thickness of abyssal oceanic crust: 10000m

Density of continental crust: 2800 kg/m3

Density of oceanic crust: 3000 kg/m3

Density of mantle: 3300 kg/m3

Density of water: 1000 kg/m3

Our course material does not include any formula for Archimedes Principle, just a brief description of how it works. So, I've googled to find a formula, but really am having a hard time understanding what it is I'm looking at. I have the basic formula, but I'm not seeing how I should use it to get what I need: Apparent immersed weight=weight-weight of displaced fluid.

I understand that the fluid here is the mantle, with density given for it, and of course the cont. crust density appears relevant, but that's about as far as I can get with this! And I don't understand why there is data for oceanic crust, water depth and density of water....

I'm assuming there are some other formulas involved in this calculation. I know thickness can be calculated from Volume=height*length*width. But nothing in the data seems to hint at length or width....?? aaah, this is so confusing, I don't know where to begin even. Any hints or tips will be greatly appreciated.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Archimedes Principle to determine height of continental crust

Have something to add?

**Physics Forums | Science Articles, Homework Help, Discussion**