Question

The use of Stokes' law for measurement of the size of soil particle depends on certain simplifying assumptions. These are:
A. Particles must be spherical, smooth and rigid
B. Fall must be unhindered
C. Particles must be of uniform density
D. Size of particles must be small compared to the size of molecules of liquid
Choose the correct answer from the options given below:

• A. A, B and D only
• B. A, B and C only
• C. A, C and D only
• D. B, C and D only

Hint:

Remember that Stokes' Law is only valid for a specific range of soil particle sizes (\( 0.0002 \text{ mm} \text{ to } 0.05 \text{ mm} \)):
- Particles \( < 0.0002 \text{ mm} \) are kept in suspension by Brownian motion.
- Particles \( > 0.05 \text{ mm} \) cause excessive turbulence, violating laminar flow assumptions.

Answer 1

The Correct Option is B