General Physics 221
posted by Mike .
During heavy rain, a section of a mountainside measuring 2.5 km horizontally, 0.80 km up along the slope, and 2.0m deep slips into a valley in a mud slide. Assume that the mud ends up uniformly distributed over a surface area of the valley measuring 0.40km x 0.40km and that mud has a density of 1900kg/m3 (cubic meters). What is the mass of the mud sitting above 4.0m2 (squared meters)area of the valley floor?

The question makes no sense to me. what does above 4.0m^2 mean?

Thats what I'm confuse about, but that is what they have from the textbook... and the answer at the back of the back is 1.9x10^5 kg.

1) get initial volume (2500x800x2)
2) divide that volume by the surface area (400x400)
3) you have depth from equation 2
4) (4x4xdepthx1900)
Visualize it as this. You first find the cube. Then they want a cube inside that cube, the base being a 2x2 which is 4 meters squared.
If Depth is 25 then 25x4x1900 = 1.9x10^5kg