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Define stokes law, Explain briefly about wet analysis.
stokes’s law • 436  views
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1) Stokes Law :-

Stokes law states that the terminal velocity of settling of spherical particle in suspension, varies with square of the diameter of the sphere, density and viscosity of the field and the density of the sphere,

$V_s = \frac{g(P_s - P_w)}{18 \mu}$

$D = [\frac{\frac{18 \mu}{g}}{(G-1)P_w}*\frac{}{}]^\frac{1}{2}$

Where $P_s = G.P_w$ is the density of solid sphere of diameter,

$\mu,P_w$ = vicosity of fluid and density respectively,

$V_s$ = Terminal Velocity = $\frac{H}{t}$

H = Distance from Surface.

Wet Sieve analysis:-

1. If the soil contains substantial quantity (about more than 5%) of fine particles, a wet sieve analysis is done.
2. All lumps are broken into individual particles.
3. A repersentative sample is taken using riffler and dried in an oven.
4. The dried sample is taken in a tray and soaked in the water.
5. If necessary, metaphosphate at the rate 2 gm per litre of water may be added.
6. The sample is stirred and left soaking for period of at least one hour.
7. The slury is sieved through 4.75 mm sieve.
8. The portion retained through 4.75 mm sieve is sieved through a 75 micron sieve.
9. The material is washed until the wash water becomes clear.
10. It is then sieved through the set of sieves of sizes 2.36mm, 2 mm, 1.7 mm, 1.18 mm, 600$\mu$, 300$\mu$, and 75$\mu$.
11. The material retained on each sieve is weighted and analyzed table of observation.
12. The result of mechanical analysis are plotted to get a particle distribution size diameter as the abscissa.
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