# Density and measurement

**Classical Mechanics**Level 2

During a heavy rain, a section of a mountainside measuring \( 2.5 \text{ km} \) horizontally, \( 0.80 \text{ km} \) up along the slope, and \( 2.0 \text{ m} \) 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 \( 0.40 \text{ km} \times 0.40 \text{ km} \) and that the mud has a density of \( 1,900 \text{ kg/m}^{3}. \) What is the mass of the mud sitting above a \( 4.0 \text{ m}^{2} \) area of the valley floor?