So here is a question that you may think has an easy answer, when it apparently actually not only does not have an easy answer, but in fact has a changing answer:
How heavy is a Kilo?
The Kilo is an important reference point for all sorts of things to do with weights and measures. The answer is that the Kilo is referenced to the weight of a rock which is kept in a vault in France. It looks like this:
The Cylinder has been the standard reference for the weight of a Kilo since 1889 (since when all the clever people in the world have not come up with a better way od measuring it.
Anyway, the other problem is that people keep picking it up, and every time someone does, it gets a little bit lighter…. and that, I’m afraid to say, is making you and me and everyone else a little heavier.
Or as Richard Steiner has been quoted as saying “if somebody sneezed on that kilogram, all the weights in the world would be instantly wrong”.