9/11 Science Club! What Are Specific Heat and Heat-Energy Content?Submitted by Sue4theBillofrights on Thu, 11/29/2012 - 22:16
Note this post deleted at original source below, this site has been displaying this pattern with 9/11 threads.
They pulled it off by dumbing us down. Education and critical thinking are vital to democracy. Science is fun!
Specific heat can be defined as the amount of heat energy required to raise the temperature of one gram of a substance, such as wood or steel, by one degree C.
Heat content is the heat energy which can be generated by a given mass a substance.
A calorie is the amount of heat energy required to raise the temperature of one gram of water by one degree C.
Converting the energy unit calories to British Thermal Units (BTUs), and the mass unit of grams to pounds, some specific heats are:
aluminum: .22 BTU/lb.
copper: .09 BTU/lb.
iron: .11 BTU/lb.
For aluminum this means it requires .22 BTUs to raise the temperature of a pound of aluminum by one degree.
Some heat content values are:
wood: 7870 BTU/lb.
paper: 6500 BTU/lb.
gasoline: 19000 BTU/lb.
For wood this means a pound of wood can generate 7870 BTUs. A pound of gasoline can generate 19000 BTUs. Therefore gasoline contains more heat energy per pound than wood.
On 9/11 it is argued that the fires did or did not reach sufficient temperatures to sufficiently weaken the steel to induce global collapse. But temperature is only one factor. The total heat content of the available fuel would have to be sufficient to raise the 95,000 tons of steel in the frame to a sufficient temperature, since steel is an excellent heat conductor and it would dissipate quickly to all parts of the steel frame. Steel is considered an ideal "heat sink."
In addition, a mechanically forced oxygen supply is required to burn fuel efficiently enough for it to reach its maximum burning temperature and deliver its maximum heat content. In order to make steel soft enough to be malleable, air must be pumped forcefully through the fuel with an instrument such as a bellows. A blast furnace gets its name from the air "blasted" forcefully with an air compressor through fuel such as coal.
In steel forming and forging, the ratio of coal or coke (refined coal) to steel required to make steel soft or to melt is anywhere from 1-to-3, to 1-to-2. This is high heat content fuel burning in an enclosed and insulated chamber at its maximum efficiency.
It is estimated that there were an average of 4 pounds per sq. foot of combustibles in the office space of the Twin Towers. There was 40,000 sq. feet of office space per floor. Therefore, the total amount of combustibles would be:
4 x 40,000 x 110 floors = 17.6 million pounds of combustibles
17.6 million lbs = 8,800 tons.
A full load of jet fuel for a 767 is about 80 tons, insignificant compared to the total amount of office combustibles.
Jet fuel is only kerosene, and has roughly the same heat content as burning plastics and office synthetics, and burns at about the same temperature in open air. Most of the kerosene blew out in the fireballs.
Therefore the available combustible fuel in one tower was 8,800 + 80 = 8,880 tons
The total amount of structural steel in the towers was 95,000 tons, 35,000 tons of it in the core bundles.
Only a small number of the floors were on fire, and those were already going out by the time global destruction ensued. However, even making the most generous of assumptions, that the planes were fully loaded with kerosene, that there was no loss to the fireballs, that every bit of combustible fuel on every floor was burning white hot at maximum efficiency (as under a forced air supply) and burning as hot as coal in a ceramics-insulated blast furnace or foundry, the ratio of fuel to steel is still only 1-to-10, not 1-to-3 or 1-to-2, as the most efficient of blast furnaces or foundries requires.
Granting the still generous assumption that a full 20 floors were on fire at white hot, maximum efficiency as hot as coal would make the ratio of fuel-to-steel 1-to-50.
We know these generous assumptions are not true. The fires were small, isolated, and already going out as evidenced by black smoke (sign of a cool, oxygen-starved fire,) firefighter radio transmissions, and people standing alive near the fires in open windows. Carbon-based life could not exist near a fire hot enough to make steel soft, but would be shriveled to carbon and water.
The plane hits themselves were insignificant. A 767 fully loaded weighs about 200 tons, whereas the mass of each tower which absorbed and dissipated the kinetic energy was about 500,000 tons. This is a weight ratio of 1-to-2500. Steel is much denser than aluminum and the planes were shredded on impact, as photographic evidence confirms.
Any damaged support columns would have resulted in load redistribution to remaining columns, of which there were 47 running continuously up the entire 110 floors.
This is why steel framed buildings do not, and have never, collapsed from fires. Steel is too strong, and open air fires do not burn hot enough, NOR IS THERE ENOUGH FUEL PRESENT WHICH CONTAINS SUFFICIENT HEAT ENERGY. Focusing on temperatures alone misses the more important concept of heat transfer. A blowtorch can reach 5,000F at the flame tip, hot enough to melt steel, but you cannot take a skyscraper down in 14 seconds with a blowtorch.
Please discuss, challenge scientific values, calculations, or assumptions. There is no such thing as a dumb question.
IMAGE: Shredded aircraft fuselage
IMAGE: Core backbone of tower under construction