Physics Help Forum A practical method to turn the planet Earth. Is there a physics level flaw in this?

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 Mar 5th 2016, 10:05 AM #1 Junior Member   Join Date: Mar 2016 Posts: 5 A practical method to turn the planet Earth. Is there a physics level flaw in this? Studying the Earth-Moon tidal force it occurred that energy from the system (moon) could be used to apply an external force (non-Earth reference frame) to turn the Earth. By affixing a horizontal lever (eg. 100m long) onto the ocean floor or an island mass, and attaching a large plate, parachute or an array of them to the lever's end, to capture (resist) the ocean tidal movement as the moon passes above each day. Collectively the force applied by the moon dragging the seawater, will slowly apply the force to the rigid lever base (the Earth itself). The ocean tide can provide the enormous energy necessary, free and scalable. The simple design requirement provides a non-maintained, energy free apparatus which will continue to apply angular momentum at the base of the lever, drawn from the moon-earth gravity. Newton laws are intact. Will come back tomorrow to discuss if any comments are made.
Mar 5th 2016, 01:38 PM   #2

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 Originally Posted by joelw Studying the Earth-Moon tidal force it occurred that energy from the system (moon) could be used to apply an external force (non-Earth reference frame) to turn the Earth. By affixing a horizontal lever (eg. 100m long) onto the ocean floor or an island mass, and attaching a large plate, parachute or an array of them to the lever's end, to capture (resist) the ocean tidal movement as the moon passes above each day. Collectively the force applied by the moon dragging the seawater, will slowly apply the force to the rigid lever base (the Earth itself). The ocean tide can provide the enormous energy necessary, free and scalable. The simple design requirement provides a non-maintained, energy free apparatus which will continue to apply angular momentum at the base of the lever, drawn from the moon-earth gravity. Newton laws are intact. Will come back tomorrow to discuss if any comments are made.
The tides are caused by the lifting of water, not pushing it horizontally, so the bar would not have any effect. From winds yes, from tides no.

-Dan
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 Mar 5th 2016, 05:08 PM #3 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,352 Actually this is exactly what causes a torque to be applied in the Earth-Moon system that caused the moon to become "tidally-locked" in its orbit (so that the same side of the moon always faces the Earth). In consequence it's known that the rotational velocity of the Earth has slowed over the millennia - the length of a day today is longer than it was in the past Hence the need for "leap seconds" (a poor term) every few years to account for the slowing rotation speed of the Earth. And as a consequence of the slowing rotation of the Earth, conservation of angular momentum dictates that the orbital radius of the moon about the Earth has increased to compensate. So yes - this torque is very real. And there are plenty of schemes for harnessing the forces of ocean tides to generate electricity, generally bases on harnessing the energy of water flowing in, and out, of tidal basins. Last edited by ChipB; Mar 5th 2016 at 05:16 PM.
 Mar 7th 2016, 02:37 PM #4 Junior Member   Join Date: Mar 2016 Posts: 5 Thanks Dan, I guess lifting will always occur as the moon is above, but I think the mass of the ocean effectively follows the moon and returns later in the day. I'll look into it specifically. Hi ChipB, Appreciate your answer. The application I mention is to turn the Earth at the poles, being the same as to raise/lower the equator. I'll try to describe the effect: An apparatus to rotate the Earth's poles by converting the linear ocean tide force daily, to rotational energy/angular momentum through captured tidal force applied to a long lever, mounted onto a fixed object such as a large rock formation on the sea floor. The lever would provide rotational force to the sea floor thus the planet, for a few hours per day, for many decades, very slowly turning the poles. Such apparatus requires no energy or maintenance. The equator would move accordingly north or south. The planet's systems would change. As an author I'm interested in this as I understand this is real/doable whereas many ideas are plausible or unknown such as giant gyro coupled to the planet, but not actually able to be carried out in the real world, and application by an individual, so not of interest to my writing. Any other thoughts I check tomorrow.
 Mar 7th 2016, 06:32 PM #5 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,352 The tidal forces of the Earth-Moon system apply pretty much east-west, not so much north-south. So the effect doesn't cause the axis of the Earth to tilt, but rather to slow the rotation of the Earth about the axis. This is because although the moon orbits close to the ecliptic (i.e. at about 23 degrees tilt relative to the Earth), any pull towards the north during the northern most extreme of the Moon's orbit is cancelled by pull to the south 2 weeks later, when the Moon has moved 180 degrees in its orbit. If you are thinking about how to change the tilt of the earth's axis using tidal forces, I think you would have to make your friction surface (ocean rocks in your example) on some sort of movable platform that could be raised and lowered depending on the Moon's position relative to the Earth. Time it just right and perhaps you could get the effect you are looking for. If you're writing a sci-fi story it might be a good plot device. If the mechanism was successful, the impact on the Earth's climate would be catastrophic.

 Tags earth, flaw, level, method, moon, physics, planet, practical, tide, turn

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