Which of the following is/are the applied forces in mechanical weathering process ? 1. Gravitational force 2. Expansion force 3. Force due to water pressure Select the answer using the code given below :

Mechanical or physical weathering involves the disintegration of rocks through various applied forces without altering their chemical composition. According to geographical sources, these applied forces are categorized into three primary groups: (i) gravitational forces, which include overburden pressure, load, and shearing stress; (ii) expansion forces, which result from temperature fluctuations (thermal expansion), crystal growth (such as salt crystallization), or animal activities; and (iii) water pressures, which are typically controlled by wetting and drying cycles or hydraulic action [1]. For instance, thermal expansion causes internal stresses through repeated contraction and expansion, while water pressure in cracks can lead to rock fracture [3]. Additionally, pressure release (unloading) allows rocks to expand vertically, further contributing to mechanical breakdown. Since all three forces—gravitational, expansion, and water pressure—are explicitly identified as drivers of physical weathering, all statements are correct [1].

Sources

1. [1] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > Physical Weathering Processes > p. 41
2. [3] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > Physical Weathering Processes > p. 40