86. El cinturón de la Tierra

Pàgines Web i articles a Internet:

http://www.bbc.co.uk/bang/handson/teaser-string.shtml
http://mathforum.org/mathimages/index.php/Rope_around_the_Earth
http://www.abc.net.au/science/surfingscientist/pdf/conundrum17.pdf

Vídeos i audios:
http://www.youtube.com/watch?v=l2E54Xiyj1o
http://www.youtube.com/watch?v=UdDFPVriuu8
http://www.youtube.com/watch?v=8WMP-2eRjQA