Does a spinning disk gain relativistic mass

[Strange]

Good point. The propoulsion system is powered by wishes rather than physics. (Does that mean a fairy dies every time the cylinder moves? #sadface)

[514void]

There are 2 disks sharing the same axle, and when the are spun up or slowed down the opposite and equal reaction is torque only.

So when you gain or lose relativistic mass by spinning something, the velocity won't change but the momentum will.

If you think that this is not physics then explain how.

[Strange]

There are 2 disks sharing the same axle, and when the are spun up or slowed down the opposite and equal reaction is torque only.

So when you gain or lose relativistic mass by spinning something, the velocity won't change but the momentum will.

If you think that this is not physics then explain how.

 

That is correct. It is your pretence that a change in momentum will magically not affect anything else that is non-physical.

[514void]

Good point. The propoulsion system is powered by wishes rather than physics. (Does that mean a fairy dies every time the cylinder moves? #sadface)

I don't see why you would think that, I don't think that wishes or fairies would stop the system working.

 

That is correct. It is your pretence that a change in momentum will magically not affect anything else that is non-physical.

not effect anything that is non-physical?

are you saying that it changes something that is non-physical and that is what cancels out any acceleration effect?

[J.C.MacSwell]

There are 2 disks sharing the same axle, and when the are spun up or slowed down the opposite and equal reaction is torque only.

So when you gain or lose relativistic mass by spinning something, the velocity won't change but the momentum will.

If you think that this is not physics then explain how.

[Strange]

are you saying that it changes something that is non-physical and that is what cancels out any acceleration effect?

 

No. Your belief is non-physical. The belief that transferring momentum, in particular from one direction to another, will have no effect.

 

"Cancelling out acceleration" is non-physical. Creating momentum from noting in non-physical. Your understanding is non-physical.

 

There is something called the "conservation of momentum". So, if you transfer energy-mass-momentum from an object moving in one direction to an object moving in another direction, then there must be an equal change in momentum, somewhere else in the system, in the opposite direction.

[514void]

so where in the the system does it create this equal change in momentum in the opposite direction?

[Strange]

so where in the the system does it create this equal change in momentum in the opposite direction?

 

It is hard to answer many of your questions because the premises are so vague. I assume deliberately, so that you can keep changing things when there is an objection.

 

But basically, in whatever mechanism you have pushing the the wheels up and down and/or transferring energy between the wheels.

 

If you were competent to do a complete, systematic analysis of your system (instead of just asserting: "it is magic and defies the laws of physics") then you would see where the flaw is. Because all you do is make vague claims, all we can say is: no.

[514void]

 

It is hard to answer many of your questions because the premises are so vague. I assume deliberately, so that you can keep changing things when there is an objection.

 

But basically, in whatever mechanism you have pushing the the wheels up and down and/or transferring energy between the wheels.

 

If you were competent to do a complete, systematic analysis of your system (instead of just asserting: "it is magic and defies the laws of physics") then you would see where the flaw is. Because all you do is make vague claims, all we can say is: no.

so you don't understand it?

 

you were confused about some points in the system, so I made it simpler so you would understand it better.

 

I made an animation, lets work with that.

There are 2 pairs of disks, they are paired so that the motor will not rotate, but it will rotate the disks in opposite directions.

there are 2 pairs so that you can compare the combined forces and so that you can isolate the forces on the disks without adding the container to the problem.

 

when the disks change velocity at the top and bottom of the container, assume that there is a force that is exerted on the disks and the container, (I'm not too good at doing animations of springs or magnets) But scientists should be able to understand it. (I hope)

Edited February 27, 2014 by 514void

[J.C.MacSwell]

so you don't understand it?

 

you were confused about some points in the system, so I made it simpler so you would understand it better.

 

I made an animation, lets work with that.

There are 2 pairs of disks, they are paired so that the motor will not rotate, but it will rotate the disks in opposite directions.

there are 2 pairs so that you can compare the combined forces and so that you can isolate the forces on the disks without adding the container to the problem.

Idealized cases for the energy transfer; referenced to the COM frame

 

If the energy for spin up comes from the pair itself, the momentum of the disk pair doesn't change, loss to battery equals relativistic gain from spin, so it won't work

 

If the energy from spin up comes from the container, the momentum of the disk pair doesn't change, loss of velocity balances relativistic gain from spin, so it won't work

 

 

If the energy from spin up comes from the opposite pair moving in the opposite direction, the momentum of the disk pair changes, but in fact the spun up pair loses some momentum; but is balanced by the changes in the other pair, so it won't work, not even backwards

 

but you can always calculate in newtonian terms for one part of the cycle, and include the extra relativistic momentum from the spin on another part of the cycle, without worrying about how it got there...

[514void]

Idealized cases for the energy transfer; referenced to the COM frame

 

If the energy for spin up comes from the pair itself, the momentum of the disk pair doesn't change, loss to battery equals relativistic gain from spin, so it won't work

 

If the energy from spin up comes from the container, the momentum of the disk pair doesn't change, loss of velocity balances relativistic gain from spin, so it won't work

 

 

If the energy from spin up comes from the opposite pair moving in the opposite direction, the momentum of the disk pair changes, but in fact the spun up pair loses some momentum; but is balanced by the changes in the other pair, so it won't work, not even backwards

 

but you can always calculate in newtonian terms for one part of the cycle, and include the extra relativistic momentum from the spin on another part of the cycle, without worrying about how it got there...

the energy for the spin comes from the opposite pair going in the opposite direction.

one takes the relativistic mass from the other without changing velocity.

It is not balanced since the momentum of the relativistic mass does from downwards to upwards.

 

even if the energy came from the container, the velocity of the disks would not change, why do you say it would?

[Strange]

Lets try an equivalent model and see where it gets us. I will assume that your spinning disks are not being driven as they move from one end of the container to the other - they are just given a shove at each end. (Is that what you are thinking?)

 

The this is equivalent to having two ice skaters (to eliminate friction) who go backwards and forwards, pushing themselves off each end of the container. The ice skaters represent your non-spinning disks.

 

With a single ice skater going to and fro, the container will alternately be pushed in one direction and then the other. No net movement.

 

With two skaters in antiphase, like your disks (till not spinning), then they will be an equal and opposite push at each end. No net movement.

 

As the equivalent to your spinning disk, one of the skaters is carrying a bowling ball. Half way down, the skater with the ball passes it to the other. At this point, the first skater speeds up (conservation of momentum) while the other (now with the extra mass) slows down (same reason). This means that when the first skater gets to the other end, they are travelling faster so, despite having less mass, they will impart the same momentum to the container. Similarly, the skater now carrying the ball, has extra mass but less velocity and so imparts the same momentum to the container in the opposite direction.

 

Conclusion: No net movement.

 

Now, you say the disks move at constant speed. This would mean they have to be propelled by some mechanism. You can go through the same process as above, with the two people standing on conveyor belts or travelators. In this case, the changes in momentum are transferred to the moving belt. The conclusion is the same: No net movement.

[J.C.MacSwell]

the energy for the spin comes from the opposite pair going in the opposite direction.

one takes the relativistic mass from the other without changing velocity.

It is not balanced since the momentum of the relativistic mass does from downwards to upwards.

 

even if the energy came from the container, the velocity of the disks would not change, why do you say it would?

Because that energy has momentum/inertia. If it is coming from the container, or the other disk pair, you need to account for it. It is the same transformed energy you are pointing to when you want to account for it when it is relativistic mass.

[514void]

so you think that spinning a disk faster or slower will change its velocity?

[J.C.MacSwell]

so you think that spinning a disk faster or slower will change its velocity?

If the energy is inputted from a different frame from that of the disk, then yes.

 

Do you think that adding mass to something will change it's velocity? Compare your answer to mine above.

Edited February 27, 2014 by J.C.MacSwell

[514void]

the motor that the disks is spun with it in the same frame, the wires that the energy goes through uses alternate current.

Edited February 27, 2014 by 514void

[Strange]

If the energy is inputted from a different frame from that of the disk, then yes.

 

This is quite important, 514void.

 

1) If the disk is physically attached to the battery which provides the energy, then as the disk is spun, there is no net change in mass (the battery loses mass and the disk gains it). Therefore there is no change in momentum and no change in velocity.

 

2) If the battery is not fixed to the disk, and the disk moves relative to it, then spinning the disk causes a transfer of mass to the disk, which means it must slow down to conserve momentum (= mass*velocity; therefore increase one and the other must decrease).

 

So, we can look at the whole system as an example of (1) above: the disk and battery are part of the same system so simply changing the mass distribution between the battery and the disk does not change the momentum of the system, and therefore the velocity of the system does not change. All you can do is move things around within it.

Edited February 27, 2014 by Strange

[514void]

no batteries.

[Strange]

the motor that the disks is spun with it in the same frame, the wires that the energy goes through uses alternate current.

 

The motor is irrelevant. As are the wires. As is AC.

no batteries.

 

Whatever the source of energy to spin the disk, the argument is the same. Substitute "the other disk" if you like.

[514void]

so this imaginary force just adds velocity directly to the disks?

[imatfaal]

!

Moderator Note

 

I think it is time for the OP to start including some calculations in this thread. The argument of the OP is completely bust - and the continued refusal to accept basic physics goes against both the spirit and rules of this site and the speculations forum in particular.

 

So 514void I am going to ask you to provide a worked example with mathematics - actual numbers are not required - but equations that comply with very well known school-boy mechanics are essential. Vague assertions will not be acceptable as it is clear that you are making connexions that are invalid.

 

For your guidance - I would heartily recommend you do this on a slow moving non-relativistic model.

 

Please make sure that you provide this worked example before too long otherwise staff will consider closing this thread.

 

[Strange]

so this imaginary force just adds velocity directly to the disks?

 

Not imaginary: conservation of momentum.

http://www.physicsclassroom.com/class/momentum/u4l2b.cfm

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

 

That should enable you to comply with imatfaal's request (and, hopefully, understand where you are going wrong).

Edited February 27, 2014 by Strange

[514void]

I was trying to find out the actual cause of the velocity change of the disks during the spin transfer stage.

but there is no physical cause, its all in the abstract mathematics, you can close this thread now since I understand where I went wrong.

[J.C.MacSwell]

the motor that the disks is spun with it in the same frame, the wires that the energy goes through uses alternate current.

Then that is where it happens. You can pinpoint it further for us...it is your design, though again, the forces involved are normally too small to be of any consideration...same with the relativistic mass. Taken together they add up to nothing, which explains why Newtonian mechanics is so useful on it's own for analyzing the vast majority of applications.

[Strange]

I was trying to find out the actual cause of the velocity change of the disks during the spin transfer stage.

but there is no physical cause,

 

Of course there is a physical cause: you are transferring momentum. (Look again at the ice skaters throwing a bowling ball to one another. Demonstrate that it is wrong, if you think there is no physical cause.)

 

Walking away saying, "I don't understand it so I win" is grossly dishonest.

http://rationalwiki.org/wiki/Pigeon_chess