Question

Imagine that you are measuring the distribution of particle sizes in a sample using the pipette method based on Stokes’ law. Determine the time that a sample must be collected with a pipette from 10 cm below the level of the suspension if the goal is to determine the contents of silt+clay (particles with diameters smaller or equal than 0.05 mm in diameter). Also determine the time to sample from 5 cm below the surface for determining the clay content (particle smaller than 0.002 mm). Assume that the density and viscosity of water are 0.998 g cm-3 and 0.009568 g cm-1 s-1, respectively, g is 980 cm s2, and particle density is 2.65 g cm-3.

Answer 1

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