energy producing experiments

[pequaide]

It is amazing to me how mind blocked your professors have gotten you people.

There is not one experiment that has ever conserved angular momentum. Yet it is worshiped without proof.

I could take ten one kilogram masses moving in a straight line; and I could catch each of them at equal distances around the arc of a circle. They would move exactly at the same speed and the momentum would not change. I don't care about your professors zero. I am not that docile that I believe such stupid things. The same quantity of force that made them move is still contained within the objects.

It is you that will miss the fun not me.

[ME]

Assuming your wheel is already up to speed, firmly attached to the ground, and the masses are held against the rim. Then one motion is converted to another.

I don't see any proof of gain in your experiment - that's basically what I try to understand here - not to proof you're wrong (but it could happen).
You say things are conserved (95%), and yet there are unexplained gains coming out of your own (I think) misapplied formulas.

We can always agree to disagree (no problems with that, and all the best to you).
And again, I just try to understand what you're doing and not to proof you wrong, and maybe I just don't understand.

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add: I thought about it, perhaps a small light is switching on here.

[Furcurequs]

I could take ten one kilogram masses moving in a straight line; and I could catch each of them at equal distances around the arc of a circle. They would move exactly at the same speed...

Ideally, yes.

...and the momentum would not change.

No, the momentum of the masses would indeed change because momentum is a vector quantity and so we have to also consider their direction of motion. When moving masses change direction, their linear momentum changes. This means that there is an exchange of momentum of the masses in your example with the system that "caught" them.

The same quantity of force that made them move is still contained within the objects.

Uh, they would still have the same speed in your described scenario and thus still have the same kinetic energy.

[Furcurequs]

Angular momentum is equal to the 'moment of inertia' times 'angular velocity'. The moment of inertia for a mass at a single radius is mrr. Angular velocity is arc velocity divided by r.  L = mrr * arc v/r so the one r in the denominator and one r in the numerator drop out for L = mr * arc v. Arc velocity is equal to linear tangent velocity; thus, mrv.

At 60 rpm for a .5m r circle and a 1200 kg cylindrical mass; the initial angular momentum is, 1200 kg * .5 m * 3.14159 m/sec = 1885. The final angular momentum is 3 kg * 12 m (r) * arc velocity. So for angular momentum conservation the final arc velocity is; 1885 / (3 kg * 12 m) = 52.4 m/sec.

Your calculations up to here seem to be okay. Notice, though, that if you calculate the kinetic energy of the 3 kg mass moving at 52.4 m/sec speed and then compare it to the kinetic energy of the 1200 kg mass moving at 3.14 m/sec at the start, you've already lost about 30% of your initial energy.

Maybe you should try more rigorous experiments and then compare your experimental results with the results of proper calculations.

[pequaide]

The 30 % loss is from the false formula of angular momentum. You are correct in that the two formulas (L and KE) do not agree with each other. And L is 96% off from momentum conservation and KE is 95% off.

Newtonian momentum conservation would require 1257 m/sec. Angular momentum conservation would require 52.4 m/sec, and kinetic energy conservation would require 62.8 m/sec.

NASA reported a 8% back spin (3 RPM back spin from 36 RPM forward spin). And they still released the tether a very high speed; near 90°. Only momentum has been observed to be transferred from small objects to large objects and 62.8 is 5% and 52.4 is 4% of 1257.

A 10 kilogram mass moving one meter per second, in a straight line, will accelerate a 10 kilogram mass at rest to .5 m/sec, when the two masses are attached with a string.

A 10 kilogram mass flywheel moving one meter per second will accelerate a 10 kilogram mass at rest to .5 m/sec, when the two masses are attached with a string.

All objects moving clockwise in a flywheel are moving in the same direction. This does not seem outside the box, to me; but apparently it is to most.

Or just drop the vector thing for a while and think outside the box. Which one of the three formulas best explains the fact that the spheres can return all of the motion to the cylinder, twice.

[Furcurequs]

Hey pequaide,

You might want to take a look at the following youtube video. The fellow made his own yo-yo de-spin device.

"Can a satellite do a yo-yo trick?"

https://www.youtube.com/watch?v=ZKAQtB5Pwq4

Perhaps it would also be a good idea for you to rig up something similar so that you could more accurately measure the rotational speed of your cylinders and spheres before the release of the spheres. Then, with a more rigorous test and more accurate data, you might be able to see through proper calculations that kinetic energy is conserved at best as it is transferred from the cylinders to the spheres.

[pequaide]

What you see in the photos of the cylinder and spheres is an experiment that is already more accurate than his. It is divided into 240th of a second. And Kinetic energy is not conserved; Newtonian momentum is conserved.

Grady Hillhouse under ‘practical engineering’
Yes it is a very good demo of a yo-yo despin device. Thanks Furcurequs

He evaluates it with the math he learned in High School. But is he correct?

If you look closely you will see that he does a full wrap of the circumference. That means the mass of the disk is about equal to 40 to one over the mass of the weights. And that would be the mass at the rim; or equal to a 390 gram rim (400 gram total mass).

What I would like to see him do is an experiment where the tether is not released and all the motion is returned to the cylinder. ‘I replaced the disk with a cylinder because the cylinder side is a much bigger target for the tether to rewind around.’

After the weights have the cylinder stopped at 90° to tangent: the weights can restart the rotational motion of the cylinder. This is not in the opposite direction; as it would be if the stop occurred before 90°.  This is about a 40 to one mass ratio between the total mass and the spheres only mass.  

I also drop the cylinder and spheres, during the experiment, so that they retain their position to one another; the weighs do not drop away from the disk.

If angular momentum were conserved (at 90°) the final velocity of the weights would only be about 10 m/sec. If Newtonian momentum is conserved it would be about 40 m/sec.

But only Newtonian momentum has ever been transferred from small masses to large masses; so the return of motion to the cylinder would confirm that Newtonian momentum is held by the weights when they have all the motion.

Ask Grady to do the experiment; he says that he is looking for more ideas. In fact I would send him $115 if he did the return motion experiment.

[pequaide]

When the motion starts with the 400 gram rim or cylinder then; .400 kg * 1 m/sec * one radius, is the starting angular momentum. And as the 10 grams moves out to one circumference (which is 6.28 radii) it must (only) have .4 units of angular momentum. The only variable is velocity; so .01 kg * 6.28 units of radius * v = .4: which is a v of 6.37 m/sec.

Even if the original rotation was 2 m/sec: 12.74 m/sec is not fast either.

I have done this experiment many times. Newtonian momentum is conserved at all points.

[pequaide]

If you want to conserve angular momentum and you keep the original point of rotation in the 390 gram rim and 10 gram weights experiment (Grady's experiment); the final velocity of the weights would be only 5.49 m/sec. If you want to use the kinetic energy formula, and have conservation, the final velocity will be 6.32 m/sec. Newtonian momentum conservation would require 40 m/sec for the 10 grams.

So which one of the rock solid Laws of Physics do you wish to use; because the other two are then wrong.

Is 14 mph sufficient to eliminate the experiment as a science fair project? Or is the speed more like major league baseball; 90 mph? When you consider air resistance it seems that the choice is obvious.

If the 10 grams has only .01 kg * 5.49 m/sec = .0549 units of momentum then how can it give the 390 gram rim .390 kg * 1 m/sec = .39 units of momentum? If this were possible then F = ma would be false; because the quantity of momentum lost by the weights has to equal the momentum gain of the rim. And the current experiments with the cylinder and spheres prove that the rotational motion is returned to the rim or cylinder.

I looked back to page 116; and I do not see any way to say it more clearly. The energy increases are huge.

Maybe you can talk Grady into repeating the experiment. Maybe others showing you the same thing will help this sink in..

[ME]

"Can a satellite do a yo-yo trick?"
https://www.youtube.com/watch?v=ZKAQtB5Pwq4

I tracked down the book he showed at this point, here it is via google: "Elements of Space Technology"
Compared formula [1.14] with the one I found earlier, and they are equal, Yay!
m = I / (2·s²) --> s=√(I / (2*m)), where s=r+l

[pequaide]

Real world experiments trump formulas; even those you don't understand.

The cold hard fact is that the motion is returned to the cylinder after the spheres have all the motion.

All real experiments prove the spheres can only return Newtonian momentum.

[ME]

Besides that:
In your experiments both Angular momentum and Rotational Kinetic Energy are being conserved which eventually equals the Linear Kinetic Energy of those spheres when the tethers are fully extended and the body (cylinder) is stationary, otherwise you need to add the cylinder's Rotational Kinetic Energy.

[pequaide]

No they are not; neither angular momentum nor kinetic energy are conserved, because we know that the motion can be returned to the cylinder, or space craft, or disk etc.

Use real numbers; for the dawn mission it would be about 20 m/sec, or there about, for angular momentum and kinetic energy conservation. That would mean that 3 kg * 20 m/sec or 60 units of momentum would bring about 1200 units of momentum back to the space craft.

Remember we have experiments were small objects give there motion to very large objects and they always give the large mass there Newtonian momentum; nothing else. Small high speed objects never share there energy or angular momentum with large objects.

The real numbers for angular momentum conservation and energy conservation in Grady's experiment is about 6 m/sec when the weights have all the motion. So again 6 m/sec times 10 grams can not accelerate 390 grams to 1 m/sec. That would be like a 390 g ballistic pendulum block being hit with 10 grams moving 6 m/sec; we know that the final velocity will be .15 m/sec not 1 m/sec.

In the double stop and double restoration of motion experiment; the motion would more than halve and halve again. In the final frames it would take 18 frames to cross the 20 mm square. But it still takes only 4 frames, it took four frame to cross at the start and four frames to cross at the finish after the spheres had all the motion twice.

When the spheres have all the energy in the double stop they have 450% of the original energy.

The other two experiments have greater increases in energy.

[ME]

I think an appropriate Latin phrase:
Non in legendo sed in intelligendo legis consistunt.
"The laws depend not on being read, but on being understood".

With a probable additional: When things don't match, we either didn't understand or we need new laws.

I could show my formula-hocus-pocus of what I (mis?)-understand, if you're interested.
(I still don't agree with assigning linear momentum to a rotating object)

[pequaide]

Kepler designed angular momentum for object under gravitational acceleration; and for satellites it work perfectly well. But it is a huge misunderstanding for things in the lab.

Kinetic energy has tremendous application; but it is not conserved.

If something is moving in an arc; and you cut the string it will move at the same rate, but in a line. It does not seem a stretch to use the same math for both motions. And if all points are moving clockwise (or all counterclockwise) then they are moving in the same direction.

This view of the universe seems to work; and isn't that what is important.