What would be the size of an imaginary EXHAUST PIPE calculated from the sum of the diameters of all that exist

Question

Here goes the question again. , For the sake of illustrating the impact we are having on the planet, What I would like to know is, based on the number of ALL vehicles worldwide that burn petroleum based fuel, including cars, ships, equipment, planes, etc PLUS smokestacks from factories, power plants, etc, what would be the cumulative size of all of these exhaust pipes, represented as one huge pipe. Also we could, with some more difficulty figure out an average of how many of these engines are running at any given time and just calculate the diameter of that imaginary exhaust pipe, spewing out pollutants. The physics handbook http://hypertextbook.com/facts/2001/MarinaStasenko.shtml lists one figure of 600 million cars worldwide. At an estimated average exhaust diameter of 1.5 inches, times that figure, the imaginary tailpipe of just vehicles alone would be 14,000 miles across? (I must be figuring this wrong!!!) Please help! Thanks

Answer 1

Flow thru a pipe is based on the area of the pipe, so if you double the flow you do not need to double the diameter of the pipe, only the area and the area varies as the square of the radius.

A 1-1/2 in pipe has an area of 1.767 square inches
1.767 x 600 million = 1060200000 square inches.
If you solve this for the radius you get 18,370 inches, so your pipe would only have to be 2 x 18,370 inche =36,740 inches =3,061 feet.

And by the way, all of the coal seams burning uncontrolled, underground in the countries of China and India put out more CO2 than all the vehicles on the road every day in the United States.

Answer 2

There are ove a million square inches in a square mile so perhaps 16 miles square or 21 miles across but exhaust is superheated and even at boiling point have a volume 1000 times that at average earth temperatures so the actiual emissions of pollution is at least 1000 times smaller than this so 0.021 mile say 30 metres.

Hey Are You a Greenpeace statistician, if not you should ask them for a job 14 000 miles when it is actually 30 metres.