“Dad, is it really so that mass depends on energy?”, C. Adler, an American physicist was asked by his son.

“No! Or rather - yes. Actually it doesn’t, but don't tell your teacher about it”, C. Adler answered.

The next day the physicist’s son stopped studying physics.


From the article by L.B. Okun, published in the “Advances in Physical Sciences”, vol. 158, issue 3, 1989, pp. 511-530

Monday, 18 July 2011

How to make a simple bamboo cannon?

Introduction:
By simple definition, bamboo cannon is a traditional firecracker made up from 4' long bamboo with inner diameter around 4" to 6".  Like other fireworks, bamboo cannons are illegal as stated in Malaysian Explosive Act 1957.


Materials and Apparatus: 

  1. 4' long bamboo
  2. Saw
  3. Calcium carbide
  4. Water
Procedures:
Bamboo cannon
  1. Cut a bamboo to 4' long.
  2. Make a hole in front at one sides until the other sides except the last bamboo barrier.
  3. Drill a small hole for ignition at one end.
  4. Place the calcium carbide inside from the front. 
  5. Pour a small amount of water in the hole.
Chemical reaction:
CaC2 + 2H2O → C2H2 + Ca(OH)2

Reaction of calcium carbide with water produced acetylene and carbon dioxide. Acetylene is a explosive gas with triple bond hydrocarbon. This reaction was discovered by  Friedrich Wöhler in 1862.
  • Use a small amount of water, the volume of water need for the reaction can be calculate from the mass of calcium carbide with the stoichiometric ratio.
Safety precaution:
Use a long rod to ignite the explosive gas.