Aluminum is used to make airplanes and Cast iron is used to make weightlifting equipment Why do the densities of these metals make them useful for these purposes?

Answer 1

Alumninium is low-density and yet has good tensile strength. In Weightlifting equipment, the primary issue is density. Different goals.

the cast iron is what makes the weights heavy, so when lifting your building muscles the aluminum made with the plane needs the strong density so it can support everything that is inside of the plane.

Answer 2

So they can see stuff