group+three

=** FOUCAULT'S PENDULUM **=

Jean Bernard Leon Foucault (1819- 1868) was a french experimentalist who proved the rotation of the Earth. For his experiments he used a BOB (a big metal ball), a string which he attached to the ceiling and a big long metal needle which he fastened to the bottom of the bob. First he spread out some ashes on the floor and then he made the the ball swing so that the needle could trace lines on the ashes. His first demonstration took place in his own basement where he used a string that was 6.5 feet long and a bob that weighed 11Ibs, his second demonstration took place in Paris in 1851 in the Meridian of the Paris Observatory, but this time he used a longer rope (36 feet long) because then the oscillations resulted slower and finally his third and last demonstration took place in the Pantheon of Paris. This is an example of the function of Foucault's experiment, the speed of the pendulum is obviously highly exaggerating.

Foucault's pendulum is conserved in the museum of arts and jobs of Paris, and lots of different museums from all around the world conserve a copy of his experiment.

Thursday, the 3rd of May, our class also made Foucault's experiment but we used a simpler method. We needed;
 * fine white sand
 * 2l plastic bottle
 * string
 * nail
 * sticky tape
 * large black sheet
 * funnel

We did our experiment in the school gym. First, our teacher with a nail made a hole in the bottom of the bottle. Then we inserted the sand inside the bottle with a funnel covering with sticky tape the hole we had made. After we tied a long piece of string to the neck of the bottle, and we tied the other end of the cord to a piece of wood in our gym. Then we spread out our big blue sheet (we had used a blue one instead of a black one) and then we took of the sticky tape and we let the "pendulum"...swing! Sand started falling out, and it formed a line, after about 10- 15 minutes we saw that the pendulum had slightly changed direction (or so it seemed) and the line shifted slightly. It had worked!

During this experiment we faced a couple complications; First of all, the sand we used was a bit wet so our teacher had to dry it in the oven, the bottle at first was also a bit wet, so our teacher had to dry that too. Next, the large sheet we had used wasn't big enough, the directions we followed to do the experiment had not specified how big the sheet should have been, so we had not known. Then, during the experiment we also found out that the sand we had used wasn't fine enough and at some point it stopped going out of the hole, we had to stop the pendulum and remove the clump of sand which had blocked the hole, and we had to repeat this a couple of times. Another problem we faced was that the bottle wouldn't swing without stopping for 15 minutes so we had to push it again and we had to push it following exactly the line it had originally created, this was very hard, because any slight movement in another direction would cause a deviation from it's natural path and in this way ruin the whole experiment. We did not exactly succeed in this, but we still did see a natural slight movement of the pendulum.

It was a very interesting experiment and it helped us understand the rotation of the Earth, it would be very nice to redo this experiment, following the observations that we did doing it the first time, and maybe the next time it would come out better.