Jam Jar Sculpture

Nails in a jam jar,
Random and unique sculpture.
Simple and complex.

Mark has been doing some DIY jobs and left these jam jars of nails on the side - I find it fascinating that each time you shake the jar you get a different "sculpture". Simple shapes in a jar and yet so many possibilities.

Then I started thinking ... do nails have kinetic or potential energy? I guess they have kinetic energy when being hammered into something, but do they have potential energy when sitting in the jar....? Any physicists out there like to enlighten me (in words of one syllable please!).

Perhaps I need to get out more?