One Calorie is Equivalent to One Gram of TNT in Terms of Energy

Daven Hiskey 6
Today I found out that one Calorie is equivalent to one gram of TNT in terms of energy.  (It is important to note the capital “C” in calorie which signifies a kilo-calorie, also known as a “food calorie” because the value listed on food labels are typically in kilo-calories.)

A Calorie is the amount of energy required to raise the temperature of one kilogram of water by one degree Celsius.  One Calorie is also approximately 4.184 kilojoules or about 1.16 watt/hours.

TNT is yet another method for quantifying energy released, but this time the energy released during an explosion.  Unlike a Calorie though, TNT is also an actual thing, namely Trinitrotoluene, which is a yellow colored substance that has some interesting properties for an explosive (see Bonus Factoids below).

The explosive yield of TNT is considered the standard measure for strength of bombs and other explosives with 1 ton of TNT equaling 4.184 gigajoules. So 1 kg of TNT then equals 4.6 megajoules, thus a single gram of TNT is equivalent in energy to one Calorie.

For further comparison, 1 kg of gunpowder will produce 3 megajoules of energy when exploding (about 2/3 kg of TNT); 1 kg of dynamite contains 7.5 megajoules when exploding (about 1.6 kg of TNT); 1 kg of gasoline produces 47.2 megajoules (about 10.26 kg of TNT), though of course requires an oxidant.

Bonus Facts:

  • TNT and dynamite are not at all the same thing, contrary to what the Road Runner and Wiley coyote would have you believe.  Dynamite doesn’t actually contain TNT, but rather is an absorbent mixture soaked in nitroglycerin, which is extremely sensitive to shock, unlike TNT; this is then wrapped in paper and voila, dynamite.
  • Alfred Nobel, the founder of the Nobel prizes, invented dynamite, which he originally was going to call “Nobel’s Safety Powder” as it was basically just a safer form of pure nitroglycerin.  This and other similar inventions made him exceedingly wealthy and also earned him the nickname, “Merchant of Death“.  The Nobel prizes were actually started by him in his will to try to improve his public image after his death.
  • Unlike some types of units of measurement, “calories” tend to be used as a concrete noun (“It’s 20 Calories”).  On the flip-side, you wouldn’t say “It’s 20 Fahrenheit’s” you would say “It’s 20 degrees Fahrenheit”.
  • The biggest advantage to TNT over many other types of explosives is that it doesn’t explode easily.  You can drop it, scrape it, even melt it (melts at 176 degrees F), which is far below the temperature it would detonate at.   This makes it handy for pouring into shells and other bomb casings.  It also neither absorbs nor dissolves in water, so it works well even in wet environments.  So even though it has somewhat of a low explosive energy release potential, these  benefits make it the explosive of choice for a variety of military applications.
  • TNT was originally created in 1863 and used as a yellow dye.  Because it was so difficult to detonate along with being a lot less powerful than many available alternatives, it wasn’t used as an explosive for many years.
  • Because of the ease of melting and pouring TNT into shells as well as how stable it is, even on impact, the German armed forces started filling their shells with TNT in 1902.  These shells were designed to pierce through armor, then explode.  This caused a lot more damage than British shells that just exploded on the surface.  By 1907, the British caught on to this and started using TNT in the same fashion.
  • TNT is poisonous and skin exposure will generally cause irritation and cause your skin to turn bright yellow or orange.
  • During WWI, munitions workers who handled TNT were called “canary girls” or “canaries” because their skin that was exposed to the TNT turned yellow.  Not only did they have a girly nickname, but prolonged exposure to TNT causes liver, blood, spleen, and immune system problems among others, sort of kicking them while they are down.
  • If you eat TNT, your pee will turn red and look like blood, though it is not.
  • The Little Boy atomic bomb dropped on Hiroshima on August 6th, 1945, exploded with approximately 15 kilotons of TNT.
  • The 1908 Tunguska Event was estimated to have produced an explosion around 1000 times that of the nuclear bomb dropped on Hiroshima.
  • Most of the current nuclear bombs the U.S. has in its arsenal are only equivalent to .3-1.2 kilotons of TNT
  • The biggest bomb the U.S. ever made had a theoretical yield of 25 megatons of TNT.  The Soviet Union however, developed one called the Tsar Bomba that was tested as large as 50 megatons of TNT with a maximum theoretical yield of 100 megatons.
  • Amazingly, if we were actually able to convert matter perfectly to energy with 1 kg of matter being annihilated by 1 kg of antimatter, the energy produced from just that small amount of matter is about 42.95 megatons of TNT.  So an adult male weighing in at around 200 pounds has somewhere in the vicinity of 4000 megatons of TNT potential stored up in their matter if completely annihilated, which is around 80 times the energy produced by the Tsar Bomba.
  • To put how much power this is in perspective, 1 megaton of TNT, when converted to kilowatt hours, makes enough electricity to power an average American home for over 100,000 years.  It is also enough to power the entire United States for a little over 3 days.  So 1 kg of some matter being completely annihilated by 1 kg of  antimatter would be able to power the entire United States for about four months.
  • On a completely baffling scale, a typical supernova explosion will give off about 10,000,000,000,000,000,000,000,000,000 megatons of TNT.

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6 Comments »

  1. Napoleon Thunderpants March 9, 2011 at 3:10 am - Reply

    “Few units of mesurement referred to as a concrete noun?”

    It’s 30 meters. It’s 40 Watts. It’s 93 kg. It’s 11 lumens. It’s 20 Newtons. It’s 16 yards. It’s 120 Volts. It’s 0.5 Amperes. It’s 11 Joules. It’s 30 Acres. It’s 3 cubic kilometers. It’s 10 kiloparsecs. It’s 10^7.5 seconds. It’s 35 Kelvins.

    Most units of measurement are expressed that way. “20 degrees Fahrenheit” is more of an anomaly than “20 Calories.”

  2. Uly March 9, 2011 at 7:18 am - Reply

    The word is “voila”. It is French, and means “there”. Voila!

    • Daven Hiskey
      Daven March 10, 2011 at 11:53 am - Reply

      @Uly: Good catch. That will teach me to check for typos at 3am. :-)

  3. Scott K March 9, 2011 at 12:45 pm - Reply

    It’s “voila”–or voilà, technically–not “vuala”! :]

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