Just for the convenience of using magnets on a surface, or is it actually practical in some other way to use a magnetic material?
This Site Might Help You. RE: SCIENCE HELP! which rocks have the same chemical composition of limestone? All I've found so far is marble, and I don't even know if that counts - please help!
Back in the day the doors were made from sheet metal because that's all they had. I think fridge magnets caught on so now fridge doors are designed with magnetic properties in mind.
This Site Might Help You. RE: why are refrigerator doors magnetic? Just for the convenience of using magnets on a surface, or is it actually practical in some other way to use a magnetic material?
Arbitrary. It's just that sheet steel is the cheapest commonly available material with the necessary properties (rigidity, humidity resistance, formability, longevity). Same reason a lot of other things are made from steel (cars, dishwashers, computer cases).
Limestone is calcium carbonate which is formed as the shells of tiny sea creatures millions of years ago. These sink to the bottom of the sea and become compacted forming chalk. (Note that the chalk which is / was used for drawing on school blackboards is calcium sulphate). These are the 'White Cliffs of Dover.' Over time and after being compressed by other layers of rock, much harder limestone is formed. Am example of this is the Portland stone used to build many public buildings in London, including St Paul's cathedral. More compression and heating by volcanic activity changes the sedimentary limestone into a metamorphic rock known as marble. The most famous marble quarries are in Italy - Carrara. Although marble is used as a work surface all three rocks have the disadvantage that adding acid causes them to give off carbon dioxide and disintegrate. Watch out for the vinegar.
