Pendulum and Nose
conservation of energy - potential and kinetic energy
What it shows:
The principle of conservation of energy ensures that a pendulum released at a particular amplitude
will not exceed that amplitude on the return swing. A lecturer's faith in their subject is put to the
test using a 50lb (22.7kg) iron ball.
How it works:
Technique is very important here. The best method to employ is to stand with your back against
the blackboard with your head also touching the board. This ensures that you don't lean forward
after release. Pull the ball towards you, holding it on the far side from your face (your hands
between it and your face may result in you giving the ball a little push...). Release by sliding your
hands aside.
Setting it up:
Galileo's Chandelier describes the setup of
the cable for the Skyhook pendulum. The iron ball clips onto this cable in the same way as the bowling ball.
Comments:
Although the iron ball is suitably massive, the bowling ball could also be used - the audience KNOWS a
bowling ball is not the sort of thing you want on a collision course with your nose; the iron ball could be
any weight. Keep your eyes open - you'll get more of a kick out of this than the audience! Rating ***