Physics; Help

[Matos de Matos]

[Matos de Matos]

Hi Guys:

I guess that my question is too confusing.

I have a feeling that when we pump a swing, the force that we add to the centripetal force to gain height, is less than if we have to lift our weight the distance gained in the swing.
Can someone resolve this for me?
Thank you
David

[Harvey]

Hi Dave,

I'll try and get back to this as soon as I can -

At first glance your last post, Frame A1; V should equal 9.899 m/s I think that wrong number got carried into the other calcs.

[Harvey]

0000

       Start    End    Difference
 X1    1470     490    980
-X1    1470    1960   -490
 Y2    2450    1470    980
-Y2     980    1470   -490
=============================
       6370    5390    980J

[Matos de Matos]

So barring all other losses, we end up with a balanced system.

[Harvey]

Zoom Image

[Matos de Matos]

Hi Harvey

Thank you, the perception is that, not static, but pushing in tuned with the swing, we could have a gain, but the force applied is for the pumping, balanced, no gain.

Thanks
David

[Harvey]

Hi Harvey

Thank you, the perception is that, not static, but pushing in tuned with the swing, we could have a gain, but the force applied is for the pumping, balanced, no gain.

Thanks
David

[Matos de Matos]

http://www.energeticforum.com/renewa...um-hammer.html
Regarding the double weights sliding, I think that the top weight when goes up, we do not have to use a force, the force to push the bottom up, will reduce the centripetal of the top one, and its goes up by centrifugal force.

That is my feeling, that when you did the math analysis you did not count for the centrifugal force of the top going up on the same direction.

Thank you

David

[Harvey]

[boguslaw]

For many physical effects we can apply the same method : take one parameter and make it changing in time . You can always choose so interesting time function that other parameter will be rising like energy for example.
Famous Tesla show ball example from his autobiography.

[Matos de Matos]

But if you consider it, you will see that something must be given up to make that happen.


2. If we use a stop and go approach, where we only raise to the midpoint and then allow the horizontal arm to accelerate it and fling it out, then we lose the potential energy of lowering it's height before it gets to the outside edge and this reduces the kinetic energy we would otherwise have. The reason, is that we used that energy to extend the arm instead by allowing the wheel to turn before the arm was fully extended.


However it is done, in order to get at the energy in the field, the conservative field needs to be separated into non conservative parts so that the energy can be extracted midpoint. A spring against gravity could provide a way to pit two conservative forces into an asymmetrical relationship the converts gravity into kinetic energy where it can be taken while letting the system refill from the field in some way.

[Harvey]

I have some things stealing my time at the moment - and I know I have neglected a few posts here at EF - but I will try and get back to them as time allows.

Looking at your pics gives me a perception that an elliptic hub of a proper size and shape could force the arm to extend and retract causing a pumping effect.

Naturally, if the contraction was sufficient to pull the weight all the way into a centric spot over the hub prior to the upswing, then total conservation of momentum occur. And conversely, if the weight was then allowed to extend out at TDC gravity could pump the system.

I think the secret there would be to make sure the elliptic only operates orthogonal to the rotation. Different sized pulleys and a belt or gears and chain or a cam lobe are all methods of getting an elliptic that could effectively change the arm lengths.

Just remember that the orthogonal pressure increases proportional to the centrifugal force during the arm contractions and that pressure often results in serious losses do to increased friction. Perhaps magnetic bearings could absorb the pressure while have zero friction

As long as you have a mechanical way to reduce the arm length orthogonally, there will be no reduction in torque from that mechanical action. But there will be an exchange between velocity and momentum.

So I think that when the arm extends, the velocity decreases and when the arm contracts in increases. This can lead to a problem if the opposing arms are connected to the same chain because the chain will transfer the velocity from one to the other unless something allows the weights themselves to move at different speeds.

We end up back at our arms being made of rope and we have that rope wrap around the tight elliptic and then release the hold pin to allow it to extend straight up like a sling shot. But then we need to make the rope stiff at the top and hold it like that throughout the down swing . . .

Nitinol Wire may work:

Nitinol wire, tubing, and sheet from NDC | Materials Sourcing

Get in touch with Nitinol Development Corp in Fremont, CA.

YouTube - Nitinol Memory Wire

YouTube - Nitinol Memory Wire

But then we have to provide a thermal reaction somehow, like perhaps solar energy to heat it. But if the energy it takes to stiffen the wire is less than the energy extracted from the gravitational fall then we have a generator.

It is all about separating the field energy into non conservative sections and stealing the energy from one of those conversions.

[Harvey]

Hi Dave,

Are you familiar with Phun?

Phun - 2D physics sandbox - Home

Phun - Wikipedia, the free encyclopedia

Some of the concepts you have could be modeled there with gravity to see how they respond.

If something looks promising, then you could try and build a 3D version to see how close it matches the design.

[Matos de Matos]

Hi Dave,

Are you familiar with Phun?

If something looks promising, then you could try and build a 3D version to see how close it matches the design.

YouTube - double pendulum 2

I sketch in ACAD without dimensions and it is easy to come up with the 3D graphics that I am posting. I am going to follow your advice, and after this one, I will learn Phun.

Thank you
David