What is an example of physical wwathering?
bits of rock rusting when exposed to oxygen and water.
wind blowing of bits of a rock over time.
limestone in rock dissolving when acid rain flows across it. oxidation of certain metals in rock
All of the examples you provided are instances of physical weathering. Here's a breakdown of each one:
1. Bits of rock rusting when exposed to oxygen and water: This is an example of chemical weathering, not physical weathering. Chemical weathering refers to the breakdown of rocks and minerals through chemical reactions. Rusting occurs when iron in the rock reacts with oxygen and water to form iron oxide (rust). This process weakens the rock, making it more susceptible to physical weathering.
2. Wind blowing off bits of a rock over time: This is indeed an example of physical weathering. Wind can carry particles, such as sand or small rock fragments, and when these particles collide with a rock's surface, they can cause abrasion. Over time, this mechanical action of wind-blown particles hitting the rock can wear it away or cause small fragments to break off.
3. Limestone in rock dissolving when acid rain flows across it: This is another example of chemical weathering rather than physical weathering. Acid rain contains acidic substances like sulfuric acid or nitric acid, which can react with minerals in rocks like limestone. The acid rain dissolves the limestone, leading to its decomposition and eventual erosion. Although the acid rain is physically flowing across the rock's surface, the process of dissolution is a chemical reaction.
4. Oxidation of certain metals in rock: This example also involves chemical weathering rather than physical weathering. Oxidation is a chemical reaction whereby certain metals, such as iron, combine with oxygen to form metal oxides. When this occurs within a rock, it can weaken the structure and contribute to its breakdown. While the process of oxidation may result from exposure to elements like oxygen and water, the actual chemical reaction involved classifies it as chemical weathering.