What it shows:
Mechanical properties of some materials change dramatically with temperature. These changes have entertaining effects on everyday objects by taking them from room temperature 300K to the temperature of liquid nitrogen 77K.
How it works:
Place your everyday objects in a dewar of liquid nitrogen for several minutes (at least until the LN2 stops boiling). Some examples to use:
1. Rubber gloves freeze solid and shatter on impact with floor.
2. Use a banana to hammer a nail into wood
3. Frozen carnations or roses presented to a member of your audience and crumpled before them.
4. Two identical rubber balls, one cooled and the other at room temperature, make a nice contrast when bounced.
Setting it up:
We use a 4L clear glass dewar about a third full. A pair of insulated gloves and tongs should be used by the demonstrator.
Fun way to introduce low temperature work or properties of materials.