Basic Physics

• Dimensions and Principles in Soil Physics:
• Gypsum Block: Electrical resistance sensor calibrated to determine (I) Soil water matric suction / content $\rightarrow$ (III)
• Pneumatic Potential: Component of soil water potential produced by external gas/air pressure differing from atmospheric pressure $\rightarrow$ (IV)
• Energy per Unit Mass: Potential expressed as energy divided by mass ($\text{J}\cdot\text{kg}^{-1}$), dimensionally $[L^2 T^{-2}]$ $\rightarrow$ (I)
• Energy per Unit Volume: Potential expressed as pressure ($\text{J}\cdot\text{m}^{-3} = \text{Pa}$), dimensionally $[M L^{-1} T^{-2}]$ $\rightarrow$ (II)
• Systematic Match: (A)-(III), (B)-(IV), (C)-(I), (D)-(II) corresponds to Option 3.

Correct option: (3) (A)-(III), (B)-(IV), (C)-(), (D)-(1))

• Soil Granular Geometry:
• In soil physics and colloidal science, an idealized porous packing model consisting of uniform particles of identical shape and diameter is designated as a monodisperse system.
• Natural agricultural soils containing a wide distribution of particle sizes (sand, silt, and clay) are polydisperse systems. (Correct answer: Option 1)

• Coordination Number in Particle Packing:
• The coordination number represents the number of neighboring spheres in direct mutual contact with any individual sphere in a geometric packing array.
• In body-centered cubic / cubic tetrahedral packing of uniform spheres, each sphere touches exactly 8 surrounding spheres (with theoretical porosity $\approx 39.54\%$). (Correct answer: Option 2)