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 :
- A.1 only
- B.1 and 2 only
- C.2 and 3 only
- D.1, 2 and 3
Correct answer
Explanation
The correct answer is D, 1, 2 and 3. Mechanical (physical) weathering breaks rocks without changing their chemistry, and all three forces drive it.
Gravitational forces act as overburden pressure, load and shearing stress on rocks. Expansion forces come from temperature changes, the growth of crystals such as ice or salt in cracks, and animal activity. Water pressure works through repeated cycles of wetting and drying. Over time these repeated stresses cause fracturing, granular disintegration and exfoliation, where outer layers peel off like an onion; frost wedging in cold regions is a common example. Chemical weathering, by contrast, changes the minerals through solution, oxidation, carbonation and hydration.
A is wrong because gravity is only one of the three forces involved.
B is wrong because it leaves out the force of water pressure from wetting and drying.
C is wrong because it leaves out gravitational force such as overburden pressure.
Exam tip: physical weathering forces: gravity (load), expansion (heat, ice, salt) and water pressure (wetting–drying).
Practice Questions
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- A.Tropical wet evergreen
- B.Tropical semi evergreen
- C.Tropical moist deciduous
- D.Tropical dry evergreen
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- B.A manure that supplies nutrients to the soil
- C.A weedicide that kills the forest roots
- D.A means of levelling the slope
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- A.Viticulture
- B.Dairy farming
- C.Shifting cultivation
- D.Commercial grain farming
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- B.Collective farming
- C.Plantation agriculture
- D.Market gardening
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- B.The monsoon lands of Asia
- C.The steppes of Eurasia
- D.The pampas of South America
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