J.C.MacSwell

Agree, but that doesn't change the fact that I think the conclusions in the link are incorrect. I don't believe Mercury orbits the common mass of the Solar System, but more so the Sun itself.

It should shift only due to momentum and outside influences, but otherwise should be on a steady path. Conservation of momentum. I don't understand the claims in the link http://solarchords.com/solar-chord-science/astrophysicists-earth-orbit-sun-or-barycentre/ Why would the inner planets orbit the barycenter? As I stated in a different thread: "Taking the 3 body problem of Sun, Jupiter, and Mercury, If we placed Jupiter far enough away the barycenter would lie outside Mercury's orbit. I think Mercury would still be in stable orbit about the Sun in that case, though of course the Sun and Jupiter would still essentially orbit about the (new) barycenter." What am I missing? Surely having Jupiter further way would give it less influence on Mercury's orbit (during any one orbit period)

I think it is not uncommon to assume lift and associated (vortex inducing) drag for airfoils with inviscid flow, by making assumptions about the separation points and wake (which is outside of the potential flow and cannot be entrained with it, as there are no shear forces and no friction), for the purpose of analyzing the flow outside the boundary layer of a real airfoil in steady flow. The assumptions are necessary (for the reasons stated by Studiot, without them no drag and no lift), and with them you can get a pretty good approximation of the lift to induced drag, above a baseline of skin friction and form drag. When an airfoil is allowed to rise this reduces it's effective and apparent angle of attack (I prefer to take the no lift angle as zero, which is different from Zet's, but either can be used) Within normal range, until the stall point is approached, induced drag is close to linear correlation with lift and angle of attack. The problem is assuming no induced drag (no lift associated drag). That's free lunch. You are assuming energy conservation does not hold from the start, so of course energies won't balance...you can use turbines and propellors based on this and design perpetual motion machines...free lunch. Zet, for your L shaped thought experiment... Assuming you get lift and associated drag, but otherwise neglect skin friction and form drag: When the airfoil is constrained that is the highest lift case...and highest drag. The result is lower exit velocity of the flow, but higher kinetic energies remaining overall, due to vortices from the induced drag associated with the higher lift. When the airfoil is allowed to rise that is a lesser lift case...and lesser drag. The result is higher exit velocity of the flow, though less K.E. overall, due to less vortices from the reduced induced drag associated with lift... and the potential gained from raising the airfoil being the difference.

I was hoping to hear back from AJB, but I am fairly sure Earth (and Mercury, though I don't believe it is exactly the same point) orbit something much closer to the centre of the Sun than the centre of mass of the Solar System. Taking the 3 body problem of Sun, Jupiter, and Mercury, If we placed Jupiter far enough away the barycenter would lie outside Mercury's orbit. I think Mercury would still be in stable orbit about the Sun in that case, though of course the Sun and Jupiter would still essentially orbit about the (new) barycenter.

Why does it not occur anyway? (it occurs more so...but baby steps) The airfoil is slowing the wind. Drag is being created. What makes you think it slows the wind more by allowing it to rise? If I do a brake stand in my car, revving the engine at full power, and finally take my foot off the brake, are you going to ask "I wonder where the energy came from to accelerate the car?"

To AJB: My bolded is incorrect, as per Moontanmans link. Jupiter moves the center of mass close (outside) to the perimeter of the Sun...I don't believe Mercury orbits that point, but something much closer to the Sun's center of mass for reasons stated

Is this correct? Surely, say, Mercury is orbiting the Sun's centre more so than the collective centre of mass? Not that they (Sun's centre of mass vs solar system as a whole) would be very far apart(still near the centre of the Sun), and still influenced of course by the other planets but it would seem to me the inverse square law would reduce the influence of the more distant planets more than a linear mass balance, with the Sun.

It all comes from increased drag, just as you suspected. In one case you are paying for lift but not using it to get work done, as you are restraining the airfoil, not allowing any motion. Efficiency is 0. 100% waste. In the other you are paying for lift and getting something from it. Efficiency > 0. < 100% waste.

There is more energy lost (eventually degrading to thermal energy) from the creation of vortices in the vertically fixed (restrained) case. The potential energy gain still comes from the wind. I think this may help you: Lets add a third case to the two I outlined in my post 49. 3. Same airfoil, same set up, except we will change the angle of attack, not by allowing it to rise as in case 2 (which changes the apparent angle) but by actually angling the nose down just to the point it will not rise. This will give us less drag than both 1. (highest drag) and 2. (now intermediate) So if you want to compare just case 2 and 3, it should work the way you feel it should.

Unless there is some source of energy to maintain it, yes it decreases. The energy does have to come from somewhere. The point is that it does not have to decrease more than when the airfoil is fixed. It is a more efficient case, since work is actually being done as the gravitational potential energy is gained. An analogy would be sitting in a car pointed up the hill with some pressure on the gas but also on the brake, restrained from going anywhere. If you take your foot off the brake, you head up the hill. There is no need to wonder why you don't need any more fuel than what you were using. You still need fuel but possibly less than before, even though you are now gaining potential energy as you get higher on the hill.

First bolded...that's correct. Second bolded...I am not showing energy is conserved, I am assuming the law of conservation of energy holds, and know there are generally frictional type losses, inefficiencies, in any real system. No thought experiment will prove it wrong.

That's right. In the frame of still air my case 1 would be equivalent to a heavier aircraft flying level at constant speed and case 2 would be equivalent to a lighter aircraft gaining altitude but otherwise at the same horizontal velocity. The heavier aircraft would require more power, and of course be adding more kinetic energy to the still air with respect to that frame than in case 2.

1. Generally speaking, if you restrain an airfoil both horizontally and vertically you will have higher drag than the same set up where the airfoil rises. 2. When the airfoil rises there will be slightly less angle of attack from the reference frame of the wing, so induced drag should be reduced. Less energy will be removed from the free stream, so the overall velocity will remain higher than in the first case Energy is of course conserved in each case. The gravitational/potential energy gain in the second case is accounted for as a loss of the free stream energy, along with other losses associated with drag, which together will be less than the drag associated losses in the first case.

"Humpty Dumpty sat on a wall Humpty Dumpty had a great fall, All the kings horses and all the kins men, couldn't put Spaghettified Humpty together again." But the BH did...

I think Fred Hoyle had that, Olber's Paradox, covered in his model of an expanding steady state Universe. So we have no infinite radiation...but instead a more limited but steady amount, depending on mass/energy density maintained by creation, and on the expansion rate... so, why could that not fit the profile of the CMB?

Are you saying a Steady State would have no CMB of any kind? Or not the one we observe?

From my experience in cold weather, dry cold air seems to keep my insulation (clothing) dryer, and damp cold air otherwise. I think this has a significant effete on the insulation value. If, say, I put on a cold but dry light down vest, it quickly seems to add warmth, where as the same vest put on damp, even if taken from inside a warm house, seems to have less effect. Evaporation cooling may be part of it, but I think the insulation value is compromised as well.

I don't believe the reference frame of a photon has ever been defined, at least in any accepted form.

This will simply create more drag most of the time. Except at relatively low speed and relatively fast downward pitch/stroke of the transom there will be more drag than thrust, and even then the upward pitch/return stroke will negate the overall effect. I have propelled a standard canoe while standing on the gunwales, one leg on each side, in calm water, but the effective area was much closer to 5 degrees than 45, and being at the surface pulled on air rather than water on the return stroke. The example in the video works very differently.

Not my forte, but it doesn't seem unreasonable that spreading out the right amount of fuel, with more surface area, with the right amount of air (stoichiometric ratio) might lead to a more complete burn and better efficiency with perhaps less pollution, and the quicker it can be done should be advantageous also, as it could be better timed with the cycle of the pistons. So, if in fact that is the case, perhaps the right sound waves would help accomplish this better than existing means alone. It may be worth investigating if it hasn't been already.

Are they discussing the formation of a toroidal planet? Or toroidal condition of a galaxy? I think the formation and stability of a planet sized toroid can be ruled out mathematically, for reasons already stated, without exotic material...with it (exotic material), it is no more difficult to fathom than a donut.

Probably best to wait until you land/crash on the ground in any event, though good point, some level of electronic entertainment must be maintained at all times these days... Seriously, what is the smallest parachute that could be deployed to allow a good chance of survival? A balloon would have to be considerably larger to create the same drag at the same speed, and have to be underneath you on landing to provide additional protection...perhaps some combination would work? The seats already (unless this has changed) serve as emergency flotation devices.

Any material not on the equatorial plane would have a gravitational component toward it, that could not possibly be balanced by angular momentum. That statement may not be exact for variations in density, but would hold for material furthest from the equatorial plane in any case. Even on the equatorial plane balance cannot be achieved, since the angular velocity must be less the farther from the centre. So it is not balanced, never mind stable, and is not possible for any mass the size of a planet, composed of known materials. The shape would be dominated by gravitational pressure...tending toward a sphere..and angular momentum...which would flatten it toward the poles

Great...now I have link envy...

http://en.wikipedia.org/wiki/Tidal_power