>>Ok, I think this one is actually relatively easy - but I find it interesting nonetheless.
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>>Assume that the Eiffel Tower has a mass of 8000 tons, and a height of 300 m.
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>>What would be the mass of a model, made to scale - accurate in every detail, and made from the same material - having a height of 30 cm.?
>
>I think we don't have enough information to determine the mass. The mass is equals the volume multiplied by (ouch, forgot the right word in English, density (?)). The density (??) is obviously the same, but how do we calculate the volume? What is the shape of Eiffel Tower and what would be its volume?

I assume it's assumed to be proportionally smaller, but of equal shape, material and therefore density. Since the volume changes with the third degree of the linear change, and we've made the thing 1000 times shorter, then the volume will be 1e9 times less - so Michael Asherman was right with 8 grams.