La versión en español (y la original) de éste post está aquí: http://viclab.wordpress.com/2007/11/30/principio-de-pascal-experimento-por-mi/
This is the experiment that I presented on my physics class about fluid mechanics. First, let’s check what does the definition of the Pascal’s Law, say:
Pressure exerted anywhere in a confined incompressible fluid is transmitted equally in all directions throughout the fluid such that the pressure ratio (initial difference) remains same.
That’s the wikipedia definition. Now, the experiment:
Demonstrate Pascal’s law and know its effects visually applied to a fluid.
- A can of soda, filled
- A pen or a nail
With the pen or the nail, make a hole (CAREFULLY!!) on the side of the can, nearly the middle.
Let the soda leave through the hole of the previous step, leaving about a quarter of the soda inside the can.
Crush the can in several spots, avoiding cutting up the can’s plate.
Hold the crushed can with your index and thumb fingers, cover completely the hole with the thumb.
Now, the fun. Turn the can or shake it a little.
After a few movements… Voilá! The can returns to its original shape.
The physics behind this. The can recovers its shape because the soda that was left in the can, releases gas due to the shaking. It’s important to say that the gases are fluids too, not just the liquids.
The liquid (soda) and the air in the can originally had a volume. Due to the soda’s gas release, that volume increases, which causes the air’s compression to keep the pressure insides.
When the gases (air and soda’s gas) and the liquid (soda) reach their maximum compression limit, the pressure increases and as the Pascal’s Law says, the pressure is equally distributed in all directions. At the moment in which the insides pressure is greater than the outside air’s pressure, the can’s material is pushed off and recover its original shape.
Curious Extra Data
- Pressure in a Can of Soda: http://hypertextbook.com/facts/2000/SeemaMeraj.shtml
- Gluep – Solid or Liquid: http://scifun.chem.wisc.edu/homeexpts/gluep.htm I know it doesn’t have anything to do with pascal’s law, but it seems to be fun :)