Eiffel tower  science puzzle
The Eiffel tower in Paris has including the tv antenna an height of 321 meter. It is made out of 7 million kg steel. Somebody would like to build a scale model of this tower with a weight of 1 kg. How tall will this scale model be? 
Answer
If the scale model weights 1 kg, it will have an height of 1,68 meter.
