how can we detect explosive or gunpowder ?
922812
When I worked at TSA they could see in the x-ray the chemical compound of certain things it would turn a bright green or orange under the x-ray light. \nWe had a man come threw the terminal who worked in an explosives factory that had to carry a card with him every time he traveled because no matter how hard he cleaned his clothes he couldn't get the compounds off his clothes hair or anything he touched. You may want to read the TSA.gov site for more info.
8881
i believe they are rockets launched just prior to the explosion. They give us an idea of how fast the explosion is expanding. hope this helped. :)
478056
There are many different "organic vapor analyzers" on the commercial market.  The specifics of each depends on the detection mechanism used.\n\nSome systems use infra-red radiation, others use mass spectrometric techniques, some use photo-ionization, and still others use a small catalytic combustion chamber to determine the concentration of flammable organic vapors.\n\nCheck for more information at places like Lab Safety Supply, or other industrial safety product companies.
203035
The sound is measured in decibels. There should be a tag inside the smoke detector with that information.
90855
Main methods --\n(1)studying the patterns of vibrational echoes returned from surface and subsurface man-made explosions;\n(2)studying data gathered by instruments during earthquakes;\n(3)studying volcanic materials
462356
It probably requires a mass spec technique.  Infrared might work.  Your detection level will be the problem.
768671
I am a paranormal investigator and have caught many things on tape.a cheap emf detector as long as it is used with caution can be found at wal-mart. in their hardware department. I use one called live wire. it is an ac sniffer just turn down the sensitivity way down and stay away from ac lines . and when you come across an emf field the tester will flash and beep.. cost about $10 have video of this in use investigator was standing still aking questions and telling spirit to make the tester beep faster or slower acording to the questions answer.. kind of cool.. \n\nhttp://www.kiestronics.com/nwopis
438403
You can use air compression if you can't find fireworks.  Rig something to blow its top and throw some top cover into the air.  Sound effects will add to it.  The container could contain smoke that you've trapped in it to release.
1167272
You can buy a simple Radio Shack police/fire scanner. Essentially the same thing, but a much lower price.
419821
must be some kind of a transducer. it could also be a laser as i am not sure whether it is sound or light waves. i think it will use a laser and a sensor to detect the reflaction and hence how near it is to an object.
1142154
hi pinku. its the science which deals with guns and bullets. when ever a bullet is fired, it gets scratched by the barrel of the gun in a particular way. it is totaly unique. no other gun can creat the same type of scratches on the bullet. its like the finger print of humans. when ever a crime takes place, it can be found out from a group of guns that from which gun was the bullet fired. and from that gun's licence number, person can be identified. thus, forensic experts use this technique to catch the culprit. \nto do this, a bullet is fired from the gun in the laboratory. it is fired at a certain angle in water tank that prevents it from getting scratched from any other outer obstacle. then the bullet is put under microscope and its photograph is taken. same is done with the bullet which is found on the crime scene. then both the photographs are matched.\nalso, it can tell the distance from which the bullet was fired. when ever a bullet is fired, it gets heated up due to gunpowder burning. this results in burning of human skin when it enters it. so, the greater the distance, less is the burn.\nit can also tell that which gun was used.\n\nhope that i was able to answer your question.\nNOTE:- bhai, kisi ko thok mat dena! hahaha......\n\ngood luck!
1023800
Gunpowder\n\nEdit:  The ingredients are saltpetre, charcoa and sulphur.  Had to look it up >: )
68440
If you atticipate the mobile phone to lose its signal (either from physical obstacles, to far from a transmitter tower, or the frequency is being jammed) an alternative way to detonate a bomb is through an infared signal. However, a line of sight is needed for the reciever to intercept the signal.
647307
Try the sonometer or the resonance experiment
750041
.You need to refer to your text or on-line to find the instructions.  A bomb calorimeter uses electricity to burn the material in the presence of oxygen.  You would need a sealed metal container (and you need to know the metal to know its specific heat), a source of electric current with exposed wires to provide the spark (be careful with the live wire!) a second larger container for water in which the first container is submerged, and a thermometer.  Good luck and be careful
536153
i believe the thing they used is called a calorometer. it involves burning the food and measuring the amount of energy that is released during combustion.
810634
http://www.orau.org/ptp/museumdirectory.htm\n\ngo to this link.  it has one of the finest museums on-line dealing with the detection of radiation...and other neat stuff