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

Mechanical weathering (physical disintegration of rocks without chemical change) involves several applied forces. Gravitational force causes mass wasting, rock fall, and downslope movement which break rocks. Expansion force occurs due to thermal expansion-contraction of rocks during temperature variations, and due to freeze-thaw action (frost wedging) where ice expansion fractures rocks. Force due to water pressure includes hydraulic action of waves, river water, and groundwater, as well as pressure exerted when water freezes in cracks. All three forces are involved in mechanical weathering, so the answer is 1, 2, and 3.