# jet engines

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#### benythejet

##### Guest
How many jet engines, with approximately 10,000 lbs of thrust each, anchored to the earth begining at the equator and lined up equally on each side of the equator from pole to pole, would it take to slow down the rotation of the earth by a measurable amount. Say, one second? Just curious

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#### billslugg

##### Guest
I need to know how long you let the engines run. <br /><br />Also need to know over what length of time the one-second rule applies. Do you want to shorten the length of the day by one second?<br /><br />Also suggest we put all of the engines on the equator. It increases the lever arm and reduces the number of engines needed.<br /> <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

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#### vogon13

##### Guest
You're looking at a closed system until the exhaust from the engines is faster than earth's escape velocity.<br /><br />So even if there was room for quadrillions of engines, the effect of all of them would be zero.<br /><br /><br /><br />{there would be some interesting alterations to the climate and wind patterns from your experiment though . . }<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

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#### billslugg

##### Guest
That is correct sir!<br />I will assume then that the engines make the entire earth atmosphere move in the opposite direction, and that no friction occurs. <br /><br />I believe the calculation and actual deployment of the engines will be easier than the environmental impact statement. <div class="Discussion_UserSignature"> <p> </p><p> </p> </div>

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##### Guest
I recall in the 1970's the Earth was slowed by high winds, isn't that a closed system?

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#### vogon13

##### Guest
Angular momentum is conserved. Moving mass from the poles to the equator (or vice versa) can change earth's rotation period, and putting the mass back will restore it. <br /><br />Tidal interactions with the moon are slowing the earth's rotation, but on a time scale vastly different than the design life time of a jet engine . . .<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

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