It wasn't easy for you to squeeze this cast-iron block. Cast iron is strong in compression. That's why early arch bridges were made of cast iron. It was easy for you to pull this cast-iron block apart. You had to push extra hard on this steel block to make it bend and break.
Steel is stronger than any other material in compression.
That's why engineers choose steel beams and columns to support most skyscrapers. You had to pull this block incredibly hard to make it break because steel is stronger than any other material in tension. That's why the cables in the Golden Gate Bridge are made of steel. Different materials have vastly different properties. This Web site was produced for PBS Online by WGBH .