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Monday, November 28, 2011

Needle magic trick

We saw here several demonstrations that give incredible magic shows. It'e a fact the balloon trick is an oldie, but is also true that sometimes the simple is the most interesting.

Before anything else: When does a balloon bursts? When the air inside is suddenly expelled, otherwise the balloon doesn't burst, just empties.
We say it bursts because it makes a big BOOM!
What we need:

  • balloon,
  • sewing pins ,
  • strong tape,
How to:
  1. Fill the balloon half way;
  2. Glue small pieces of tape, 2, 3 ,4 ... as you wish, it will depends on the number of pins you have and on balloon size;
  3. Make sure that the tape is well glued to the balloon, air bubbles will lead to a big BOOM!;
  4. Gently, but without fear, stuck a pin in the center of duct tape;
  5. Repeat this to all pieces of tape in the balloon.

What happens?
Balloon doesn't burst!

The balloon burst when the air is suddenly forced out the rubber coat. In this demonstration it doesn't burst because we made a "seal"- with the tape- around the spot where we pin it, here the rubber is reinforced.

We can try to take the pins of the balloon, which will make the balloon emptying slowly. While the tape
resist the balloon will not burst.

Try to observe the rubber ripping beneath the tape, near the spot where you place the pin, when the air pressure, inside the balloon, overcome the tape "seal" we can observe a small tear underneath the  tape.  The more the balloon is filled, the greater the pressure is, and faster the pressure overcomes adhesive and tear appears, the next step is Bang!

  • Glue the tape pieces apart from each other;
  • Use light color balloons, it will be easier to observe;
  • Use strong tape, works best
You can try to understand better this pin magic:
  • Use several balloons, same sized; fill them with different air quantities. Use a chronometer and see how long the air pressure takes to beat the rubber "seal". 
    • What is the ideal volume air?
  • Use more then 1 pin, and on each balloon vary the space between the tape pieces. 
    • Does this have any influence on the time the balloon takes to lose the air? 
    • And does it simply lose all the air or does it burst?

Et voilá!
It's magic


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