What is the definition of physical weathering? View Available Hint(s) What is the definition of physical weathering? Mechanical processes add chemicals to create new substances. Mechanical processes break substances into smaller pieces. Chemical reactions produce new substances. Rock is dissolved by chemicals. Rocks fall apart.

Mechanical weathering refers to the breakdown of rock into smaller (finer) particles. These processes mostly takes place near the earth's surface. Some of the mechanical weathering processes include-

(a) Freeze and thaw method- This process takes place in a cold type of environment. When rainfall occurs in these areas, then the water is accumulated in the fractures and the joints of the rocks, which freezes at night time due to the low temperature. Due to the freezing, the volume of the water expands as a result of which the rocks are broken apart.

(b) Insolation weathering- This is a process by which the rocks are heated during the day time and cools during the night time. Due to this continuous process, the rocks are disintegrated.

(c) Biological weathering- It is a process that allows the rocks to break by the plants and animals, including the microbial organisms. The plants when grows through the rocks it creates stress as a result of which the rocks are broken apart.

Thus, the correct answer is option (2).