Similarities between glass and plastic.....?

Question

that allow them to be substituted for eachother...
and
what properties make them different from eachother?

Answer 1

Glass is an amorphous solid. Many plastics also are. Glass and amorphous plastics are transparent, so one can use them for windows. Glass is brittle and shatters to sharp edges. Even amorphous plastics have "give" and do not break. Polystyrene packaging has "give," but if you try to cut open the packages, you get sharp edges that can cut a person. Glass is dense, so glass parts are heavy. Plastic is less dense, so plastic parts of the same size are lighter. Glass is expensive. Plastic is cheap. In costing it out, it is good to consider $/cu cm. Glass or plastic are used to cover a certain amount of volume or area. So that will be cheapest that cost less $/cu cm.