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This is a very easy experiment to do
and it will surprise quite a lot the young audience.
We take a cardboard box, for example a shoe box.
The closed box is shown to the viewers
who thus can notice that there is nothing wrong with it.
We put the box down on the edge of the table.
While everyone expect to see it fall,
the box remains in balance even if it widely overhangs the empty space below.
We take off the lid and show the inside of the box to the viewers: it is empty.
Obviously, the explanation is very easy:
the box has a double-bottom under which an overload has been stuck,
for example some nails heavy enough.
Some cardboard wedges need to be placed
to hold the double-bottom firmly in place and make it undetectable.
The overload has rejected the centre of gravity of the box very close to its edge,
which allows it to remain in balance,
even if it overhangs the empty space below.
Production: University of Lille 1 – Science and technology
SEMM Multimedia Service – University of Lille 1.
The Online Thematic University for Sciences
Teachers Researchers: Jean-Marie Blondeau; Bernard Bonnel
Project coordinator (shooting and editing): Bernard Mikolajczyk
Technician: Gérard Destrun
Voice over: Alain Nempont
Contact: semm@univ-lille1.fr