Question

Which is heavier 1kg of iron or 1 kg of feathers?

Which occupies more volume 1kg of iron or 1kg of feathers?
Which has a larger density, iron or feathers?

Answer 1

-- On Earth, 1 kg of anything weighs 9.81 Newtons (2.205 pounds). It doesn't matter what substance comprises the kilogram.

-- Although their weights are identical, any mass of feathers occupies more volume than the same mass of iron, no matter where they happen to be located.

-- Iron is more dense than feathers, and more dense than a lot of other substances as well, too.