Driving on the 87 Octane yields 20 mpg so the driver is able to pass 200 miles for $31.00 dollars and the cost per mile will be $0.16. The example above is simplified but shows that even though the entry cost is lower and in the end, the gas will end up costing more.
Weathering of rocks is caused by chemical and mechanical means, and the types of weathering are therefore generally classified as chemical or mechanical (also known as physical).1  Slightly acidic rainwater can react with rock surfaces, dissolving them over time.ockhound. Weathering of rocks is caused by chemical and mechanical means, and the types of weathering are therefore generally classified as chemical or mechanical (also known as physical). 1  Slightly acidic rainwater can react with rock surfaces, dissolving them over time.
Biological Weathering vs. Physical and Chemical Weathering. The three different types of weathering are physical, chemical and biological. Physical weathering is caused by mechanical forces, without any change to the makeup of the rock.icroorganisms and Lichens. Not all biological weathering occurs visibly. Many microorganisms in the soil and on the surface of rock can contribute. Some bacteria derive nutrition by taking a combination of nitrogen from the air and minerals -- such as silica, phosphorous and calcium -- from rock.