Ok, I think this one is actually relatively easy - but I find it interesting nonetheless.
Assume that the Eiffel Tower has a mass of 8000 tons, and a height of 300 m.
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.?
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
