Why Gravity wheels don't violate the laws of Physics

[daxwc]

Mass itself has no direction. In space you become weightless, but you have the same mass as you do on earth. Weight is mass plus gravitational pull. The rate of gravitational acceleration does not depend on the wieght of the object being pulled on by gravity.

[rlortie]

Graham,

Isn't weight the same as mass in a gravity field?

No it is not! Mass is a unified body of matter with no specific shape. The physical volume bulk of a solid body.

Physics definition is; The quantity of matter that a body contains, not dependent on gravity and therefore different from but proportional to its weight.

IMO Bessler was using this when he discusses spheres of the same mass and shape but with different density of weight. a mass of Styrofoam will way less than a mass of lead of the same size and shape. That is to say "weight" is based on density of mass and cannot be compared to shape or size of mass.

Ralph

[Michael]

In everyday situations, the mass of an object is proportional to its weight, which usually makes it unproblematic to use the same word for both. Distinguishing them becomes important for measurements with a precision better than a few percent, due to slight differences in the strength of the Earth's gravitational field at different places, and is essential when one considers places far from the surface of the Earth, such as in space or on other planets.

Typically mass is volume by density.

[graham]

The impact is dependent on wieght not mass

I still don't agree with this.

We were talking about a weight falling from a helicopter I believe. From a practical point of view in this example when we talk of weight we talk of mass.
Halve the mass and we halve the weight.

I agree that weight and mass are not the same but in a gravity field they are directly proportional, so the above quote doesn't make sense

Graham

[Deven]

Isn't weight the same as mass in a gravity field?

On earth, yes you could say that mass and weight are the same. In any gravity feild, however, no.

1kg of weight on earth is equal to 1kg of mass anywhere. 1kg of weight on the moon, however, would probably weight about 6kg here, and the mass would still be 6kg. Weight is a product of the gravitational field, mass is not. The confusion lies in that our mass measurements are relative to our own gravitational field.

Edit: Didn't mean to beat the dead horse. :)

[rlortie]

Michael,

In everyday situations, the mass of an object is proportional to its weight, which usually makes it unproblematic to use the same word for both.

It is unproblematic as weight is proportional not to size of mass but density.
The weight of a mass including air is measured at X # per cubic unit. which
will vary with altitude, heat, and humidity. A green or fresh cut board will weigh more than a dry one of the same size and physical mass.

Typically mass is volume by density.

Right on!

Ralph

[Michael]

Ralph the quote was from wikipedia, the other mine.

[Fletcher]

Lets sideline the helicopter hovering example for a while but keep the rest of the setup & imagine the tethered 1 kg weight hanging from the roof - now we won't get confused with the fuel PE energy added to the system, blade inertia causing lag in balancing of forces, reaction times not allowing instantaneous equalization of forces etc - we can now treat the example as just a simple isolated closed energy system & forces.

The box on the scales registers a certain weight & it has a certain energy associated with it - this is the PE of the suspended 1 kg weight/object & no KE at this time - when the 1 kg object is released the scale will read less, as others have said, while the object is falling - as it falls the PE of the object is being converted into KE - because the object has inertia it will impact the bottom of the box with a force proportional to the square of its velocity, as we know - the scale is a force meter & will spike at impact then settle down to record the combined weight force of the apparatus - the total experiment will have less PE than it started with - if we consider the energy required to lift the object to its tethering point the energy in the system is constant i.e. a changing mix between PE & KE [linear trading one for the other].

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The Mass of a body/object is the quantity of matter it contains.

Objects are usually only considered to have weight when in a gravity field context [different 'weights' depending on the strength of the gravity field they are in] - objects always have Mass - this is what dictates the objects Inertia - inertia is a physical characteristic of mass which allows KE to be measured, else you would have no impact force to measure - that's why your space suit can be holed by a fast moving speck of dust [it has mass & importantly inertia, but not weight].

The Weight of a body is the force it exerts on anything which supports it & normally, it exerts this force owing to the fact that it is itself being attracted towards the earth by the force of gravity.

EDIT: it could be said that the weight of an object can be increased in a gravity field if the object is revolving around an axis & so developing Centrifical Forces [the number of 'g's' in a turn]. In that instance the CF vector is added to the weight vector to give a resultant force vector.

[winkle]

. .

[daxwc]

Is it safe to say that from this argument, from a gravity wheel perspective, that as soon as a mass is released or goes into free fall that is what causes back torque. It is caused by the negative weight to the system during free fall. Also that the mass does not have to be in free fall to have this negative weight, but by just the action of trying to harness gravity.

If it is then I have been trying to get rid of back torque the wrong way.

[Fletcher]

Is it safe to say that from this argument, from a gravity wheel perspective, that as soon as a mass is released or goes into free fall that is what causes back torque. It is caused by the negative weight to the system during free fall.

Yes .. if the weight is released into free fall it no longer has a physical connection to the wheel & won't again until it impacts the interior of the wheel after its fall.

In its very simple form it is the same a a see-saw [teeter-totter] where there are identical masses balanced around a fulcrum [equidistant from that fulcrum]. If one mass is 'disconnected' it falls, accelerating & gathering KE, so from a balance perspective it is "missing in action" as it cannot provide the equalizing torque to the opposing mass which still is 'connected' & applying its torque to the fulcrum/pivot. That means there is back torque in the see-saw [more aptly described I suppose as asymmetric torque] but torque nonetheless in the opposite direction to the direction of fall - also that means the see-saw/wheel will now be temporarily robbed of momentum from its direction of rotation, if it had rotational velocity to start with.

Also that the mass does not have to be in free fall to have this negative weight, but by just the action of trying to harness gravity.

Just trying to harness gravity means a physical intervention within or even outside of the wheel system. Lets use a ramp as an example - this ramp might try to take the mass to a greater radius after 12 o'cl on a CW wheel to create greater down going torque or it might be a lifting ramp after 6 o'cl to bring a mass closer in towards the axle so it creates an asymmetry of torque on that side - the ramp might be quite separate from the wheel - as soon as the weight connects the top ramp to 'push/lift' it outwards it must 'carry' a portion of the masses weight - immediately it cannot apply its full compliment of torque that it had before the intervention - the ramp at 6 o'cl to move the mass closer to the axle must also 'carry' a part of the masses weight on the ascending side of the wheel - this seems good because we want to have less negative torque on this side, but in order to bring it closer to the axle to get that asymmetric torque we have to physically lift the mass some vertical component - this requires all the energy we got from the descending side imbalance plus a bit extra for ordinary losses. In a closed energy system you cannot get more energy out than went in !

I am well prepared to eat lashings of humble pie should someone prove the argument that gravity alone can power a wheel.

If it is then I have been trying to get rid of back torque the wrong way.

Back torque is a big issue - some think that a one-way rachet might help to physically stop the wheel counter-rotating while a mass is deployed on the down going side but thats a discussion for another thread & has been discussed before by LIB.

[jim_mich]

I am well prepared to eat lashings of humble pie should someone prove the argument that gravity alone can power a wheel.

ME TOO! I'll be standing there with you.

[ovyyus]

...and me!

[scott]

Count me in for some lashings as well :-)

[rmd3]

I am well prepared to eat lashings of humble pie should someone prove the argument that gravity alone can power a wheel.

But has it been disproved?

What about Airy's paper? Didn't that prove it was mathematically possible? And did Bessler's wheel prove it was physically possible (and his comments support how it worked?)?

With all the mechanisms of transferring force or moving weights around with minimal loss via linkages, levers, belts, gears, pulleys, springs, ramps, etc. To me, it seems highly likely that forces could be manipulated in such a way as to keep a wheel rotating on its own.

I haven't explored this question, but it has been on my mind : was Airy's description of the problem and the solution the same thing as a resonance problem in differential equations?