[JP]

So if the cows let 'em rip with high enough velocity, could they eject the earth's atmosphere into space?

[Geezer]

So if the cows let 'em rip with high enough velocity, could they eject the earth's atmosphere into space?

You'd probably only get enough acceleration to do that if the methane was ignited (very carefully.)

[Geezer]

......or, we could turn it around a bit and consider how many cows it would take to release enough methane to form an explosive mixture that would consume all of the oxygen in the Earth's atmosphere in a single explosion.

[damocles]

The greenhouse gases in the cows' flatulence will likely cause global warming, which will start to melt the Greenland and Antarctic ice caps, which will lead to a net redistribution of mass from poles towards equator, which will slow the earth's rotation (like a skater putting her arms out). No need to even get your cows to line up!

[Airthumbs (OP)]

Anyone know what the current world pop. is of cows and how much gas they produce on average each day.  Of course we should include all ungulates but the task of calculating their output is inflammatory!  And what is the amount of methane needed to cause the possibility of combustion at sea level in our atmosphere?

I have not heard of a farmer blowing up their cowshed due to methane buildup?

[Geezer]

I have not heard of a farmer blowing up their cowshed due to methane buildup?

I did read of a case not so long ago where several people on a farm were asphyxiated by methane. If I remember, it was released from a slurry pond.

http://www.usatoday.com/news/nation/2007-07-04-va-farm_N.htm

[Bored chemist]

There's a James Herriot story about a cow with bloat setting fire to a shed when they treated it.

[Airthumbs (OP)]

I have not heard of a farmer blowing up their cowshed due to methane buildup?

I did read of a case not so long ago where several people on a farm were asphyxiated by methane. If I remember, it was released from a slurry pond.

http://www.usatoday.com/news/nation/2007-07-04-va-farm_N.htm

That is quite a sad story Geezer  [:-[]

I think I have read all of James Herriot's Vet books.... used to make me laugh a lot!

[Bored chemist]

The conclusion seems to be that cow farts don't speed the earth up (no matter which way they are facing) for any length of time and they may slow it down (depending on whether or not the methane levels in the atmosphere attributable to cows are stable).

[JP]

The conclusion seems to be that cow farts don't speed the earth up (no matter which way they are facing) for any length of time and they may slow it down (depending on whether or not the methane levels in the atmosphere attributable to cows are stable).

Wasn't the conclusion that they can speed it up for a very short length of time (that we never determined), but that this effect would be short-lived due to friction/air resistance?

[damocles]

I think the issue that Bored chemist had picked up on was that the consequences of the methane buildup in the atmosphere slowing down the earth, small as they are, far outweighed any effect, transitory or not, due to reactive torque.

Or in simpler language:
-- A lot of cows facing in one direction and letting rip might (or might not) provide a short term rocket-like kick that would speed up the Earth's rotation.
-- That effect, even if it existed, would be minute.

HOWEVER

If the polar icecaps of the Earth were to melt a little, there would be a movement of material from the poles to the tropics.
-- This would slow the Earth's rotation by increasing its moment of inertia
-- The effect would also be minute, but much greater than that arising from any rocket-like torque
-- Such a melting could be (and probably is being) triggered by a build up of methane and CO2 in the atmosphere.
-- Cow flatulence is triggered by methanogenic microorganisms --  C6H12O6 (sugar/cellulose) --> 3 CH4 + 3 CO2

[Bored chemist]

OK, Poor phrasing on my part.
When I said "for any length of time" I meant it in the vernacular sense (i.e. "any significant length of time") rather than the literal sense.

[JP]

BC: then I agree.

[Geezer]

Well, see, it's pretty obvious really. The question was;

"Can cow farts make the Earth rotate faster?"

In fact, cow farts actually make the Earth rotate more slowly. This is because they are continuously converting "Earth mass" (grass etc.) into "atmospheric mass" in the form of methane. This results in a slight, but real, increase in the moment of inertia of the Earth/atmosphere system.

If all the cows were to suddenly stop producing methane, the moment of inertia would decrease, and the Earth would take less time to rotate.

[Airthumbs (OP)]

What you are forgetting is total historical contribution for cow farts!  A lot of cow fart is locked up in the form of methane in massive quantities below the ocean and vast areas of land currently in a state of permafrost and melting! 

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You might say that the energy from a cow fart is dissipated, and that would be in line with the theory of infinite dilution.  One molecule of methane, absorbs 20 times the amount of infra red radiation then that of Carbon Dioxide, making it a far more efficient green house gas.

So all that trapped cow fart is going to be released into the atmosphere.  If all of the gas was exploded in one place on earth, the resulting explosion would definitely have an effect of the earths rotational axis, haha!

Admittedly all the cows over history passing gas have not been standing in the same direction whilst doing so.  []

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Just look at all that energy! What a waste...  []

[CliffordK]

If everyone stood up in a parked school bus (in neutral) and threw their book bags at the same instant towards the back of the bus, it would (theoretically) propel the bus forward for an instant.  Until the books slammed into the back of the bus.  At which point the movement of the bus would stop again.

Likewise, if everyone stood up, bent forward, and let some flatulence go...   
Well, the net effect on the bus would be nil, but people might be sent screaming out of the bus!!!!!!!

If you consider the earth as a closed system like the school bus, then the net effect will be nil.  However, if it was time synchronized, one might be able to imagine a slight bump, returning to zero, like the instant while the books were still flying through the air.

[Bored chemist]

Great analogy; I wonder if Geezer accepts it.

[Geezer]

Great analogy; I wonder if Geezer accepts it.

Almost, but not quite.

The bus was accelerated, therefore it was "made to move faster". Then it slowed down again and stopped.

However, the bus did not return to its original position, so we can't say the net effect was nil.

[Airthumbs (OP)]

What if the bus was propelled by a certain gas produced by the animal in question?  []

[Geezer]

What if the bus was propelled by a certain gas produced by the animal in question?  []

Well, then it would have to be green, wouldn't it?