1. Stokes Law
2. Discuss the hydrometer method of texture determination
3. Draw a textural triangle
4. Using the triangle determine the class of the following soil
i 40%sand, 30%silt , 30%clay.
ii 10%sand, 60%silt, 30%clay.
1. Stokes Law refers to a mathematical equation that describes the motion of spheres through a viscous medium, such as a liquid or gas. It states that the velocity of a sphere falling through a fluid is directly proportional to the force of gravity and the square of the sphere's radius, while inversely proportional to the medium's viscosity.
2. The hydrometer method of texture determination is a technique used to determine the relative proportions of sand, silt, and clay in a soil sample. It involves dispersing the soil particles in water and then using a hydrometer, which is essentially a specialized floating device, to measure the settling rate of the soil particles. By analyzing the settling rate, the percentages of sand, silt, and clay can be determined based on predefined particle size ranges.
3. Here is a simplified representation of a textural triangle:
Sand
Loamy Sand
Sandy Loam
Loam
Silt Loam
Silt
Clay Loam
Sandy Clay Loam
Silty Clay
Clay
4. Using the textural triangle, we can determine the class of the following soils:
i) For a soil with 40% sand, 30% silt, and 30% clay:
- Start at the 40% sand mark on the horizontal axis.
- Move vertically up to the 30% clay mark on the diagonal boundary between sand and clay.
- From the point where the sand and clay boundaries intersect, move horizontally to the left until you reach the 30% silt mark.
- The soil falls within the sandy clay loam class.
ii) For a soil with 10% sand, 60% silt, and 30% clay:
- Start at the 10% sand mark on the horizontal axis.
- Move vertically up to the 30% clay mark on the diagonal boundary between sand and clay.
- From the point where the sand and clay boundaries intersect, move horizontally to the right until you reach the 60% silt mark.
- The soil falls within the silty clay class.