How does the Sun contribute to physical weathering of rocks on Earth's surface?

• A. By providing energy for chemical reactions that break down rocks
• B. By directly dissolving minerals in rocks through radiation
• C. By causing repeated heating and cooling, leading to expansion and contraction of rocks
• D. By increasing the amount of rainfall that erodes rocks

Answer: (C)

Verified step by step guidance

1. Understand the concept of physical weathering: Physical weathering refers to the mechanical breakdown of rocks into smaller pieces without changing their chemical composition. This process is often driven by environmental factors such as temperature changes, water, wind, and ice.
2. Identify the role of the Sun in physical weathering: The Sun provides heat, which causes temperature fluctuations on Earth's surface. These fluctuations can lead to the expansion and contraction of rocks.
3. Explain the mechanism of expansion and contraction: When rocks are heated by the Sun during the day, they expand. At night, when temperatures drop, the rocks cool and contract. This repeated cycle of expansion and contraction creates stress within the rock structure.
4. Describe how stress leads to rock breakdown: Over time, the stress caused by repeated heating and cooling can cause cracks to form in the rocks. These cracks grow larger with continued temperature fluctuations, eventually causing the rocks to break apart.
5. Clarify why the other options are incorrect: The Sun does not directly dissolve minerals in rocks through radiation, nor does it provide energy for chemical reactions (which is part of chemical weathering, not physical weathering). Additionally, while the Sun influences the water cycle, it does not directly increase rainfall to erode rocks in this context.