Author Topic: EM Drive Developments Thread 1  (Read 796004 times)

Offline Mulletron

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Re: EM Drive Developments
« Reply #3080 on: 11/10/2014 09:11 AM »
I can see that the experimenters recognize heat contributions to the thrust plots. Look at the screen shot below. Table 2 isn't reporting 130uN of thrust for TE012, it is reporting just 55uN, after subtracting artifacts from the total 130uN peak.

They recognize da heat, which is apparent by that gentle rise over 30 seconds followed by a gentle fall over 30 seconds.

The sudden rise and sudden fall is the real thrust here.
.../...


If it were that sudden, why there is not the characteristic overshoot magnitude clearly visible for the calibration pulses (of similar magnitude) that are known to be "instantaneous" ?

You must see there is a huge difference between the result of rectangular force signals of calibration pulses vs thrusts pulses : the explanation is that for the later the rise is steep but not as steep. Still working on quantitative estimates but this is strongly hinting a time constant (time to asymptotically reach the plateau) that is likely much higher than anything electromagnetic in nature. Likely below 2 seconds but likely more than .1 s (analysis will tell).

There is an overshoot with the "thrust" impulse. Blue circles below. Why do you feel it needs to be the same magnitude as the cal pulse overshoot? Do they share the same dynamics? I would say not.

In the screenshot below, why do you feel the blue bounces and green bounces should be equal? Do they share the same exact kinematics? Is the calibration system intended to match the kinematics of the test article? I think not. It is just to provide a stable known reference for force measurements. And to make sure the test bench is measuring the same every time. I wouldn't go out on that limb with such little info available. The test article and the calibration system overcome the inertia of the test rig in different ways. There's no need to throw pages of math at a problem where there is no information to support anything. We don't even know the mass of a single thing in that test chamber.

There isn't enough information to support such an exhaustive analysis because lack of knowledge leads to hasty assumptions, thus a bad result. The best we can get from this paper is the knowledge the thrust pulses rise and fall suddenly, just like the cal pulses. And that there is a "bounce." The fact that there is more or less bounce is inconsequential.


That kind of over nuking it analysis is tantamount to me trying to calculate how fast my car's windows roll up simply by reading a car advertisement in a magazine.
« Last Edit: 11/10/2014 09:54 AM by Mulletron »
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Offline frobnicat

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Re: EM Drive Developments
« Reply #3081 on: 11/10/2014 09:55 AM »
I can see that the experimenters recognize heat contributions to the thrust plots. Look at the screen shot below. Table 2 isn't reporting 130uN of thrust for TE012, it is reporting just 55uN, after subtracting artifacts from the total 130uN peak.

They recognize da heat, which is apparent by that gentle rise over 30 seconds followed by a gentle fall over 30 seconds.

The sudden rise and sudden fall is the real thrust here.
.../...


If it were that sudden, why there is not the characteristic overshoot magnitude clearly visible for the calibration pulses (of similar magnitude) that are known to be "instantaneous" ?

You must see there is a huge difference between the result of rectangular force signals of calibration pulses vs thrusts pulses : the explanation is that for the later the rise is steep but not as steep. Still working on quantitative estimates but this is strongly hinting a time constant (time to asymptotically reach the plateau) that is likely much higher than anything electromagnetic in nature. Likely below 2 seconds but likely more than .1 s (analysis will tell).

There is an overshoot with the "thrust" impulse. Why do you feel it needs to be the same magnitude as the cal pulse overshoot? Do they share the same dynamics? I would say not.

I would say yes. Those overshoot are the result of the response of the measurement system, which is the displacement of the beam of the balance, not of the excitation, which is a force imparted on the beam of the balance. So the calibration pulses and thrust pulses share the same dynamic because they share the same balance, if one is to make it ring in a particular way, then the other should make it ring in a similar fashion if it is to be of similar nature (as far as temporal evolution of imparted force is concerned).

What is reported in the curves is a measurement_function of the force signals, not the signals themselves.
So in one hand we have   measurement_function( cal_pulse(t) )
And in the other we have   measurement_function( thrust_pulse(t) )
The measurement_function is the same, it is given by the dynamics of the balance, not the mechanics of the pulses.

Clearly : 
cal_pulse(t) ≈  thrust_pulse(t)
=> measurement_function( cal_pulse(t) ) ≈ measurement_function( thrust_pulse(t) )

By contraposition :
measurement_function( cal_pulse(t) ) measurement_function( thrust_pulse(t) )
=> cal_pulse(t)   thrust_pulse(t)

Why would a thrust imparted by electromagnetic coupling to something (aether, mach effect on local horizon, whatever) would be any different to a calibration force (of similar magnitude) given by electrostatic fins ? A real thrust (not an artefact) should be as "instantaneous" as the calibration pulses, so it should give the same kind (same allure) of response from the balance.

There are always caveats of course, if you want, maybe the power-on of the microwaves is not instantaneous. If the amplifier takes .2 s to get to full power then this mystery is explained. But this "undershoot" signature appears to occur more for the low power experiment (at 2.6 W) than for the higher power (around 16.8W) : this would be a natural parameter dependency for a thermal effect, while it would be a very contrived consequence of an amplifier power-on delay (the amp would take more time to reach nominal power when nominal power is lower).

Quote
The test article and the calibration system overcome the inertia of the test rig in different ways.

How ? Why ? Come on, that doesn't make sense. The point of application of the force may be a little different, but a force on a beam is a force on a beam. You are eating too much fringe science : inertia isn't to be "overcome" in different ways, there is just this   F = m*a thing that relate a force (whatever its origin) to an effect (an acceleration).

« Last Edit: 11/10/2014 10:08 AM by frobnicat »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3082 on: 11/10/2014 09:56 AM »
Well it does take time for energy to build up in the cavity. The fact that there is a sudden rise and fall when rf is on and off is enough. Just like the cal pulses suddenly rise and fall. It is obvious that the impulse from the cal system acts more quickly than the test article. It is an instant on/off device. The cavity needs a tiny bit more time. Now do you see why I said that the cal system and the test article overcome the inertia of the test rig in different ways? There isn't enough granularity in those photos to discern between those times. The rise times of the thrust pulses and cal pulses are nearly identical.

This isn't fringe science, just common sense. Common sense first, then math. Not the other way around.

What is important, once you take into account of heating/cooling, is if you draw a line through middle of the leading and trailing edges (blue lines), you get a mirror image. That means that both the cal system and the test article are symmetrically effecting/being effected by the magnetic damper around back. And they are.

There isn't a problem here.
« Last Edit: 11/10/2014 10:14 AM by Mulletron »
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Offline frobnicat

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Re: EM Drive Developments
« Reply #3083 on: 11/10/2014 10:04 AM »
Well it does take time for energy to build up in the cavity.

Yes it does. On the order of Q * typical_length / c = 20000 * .3 / 300000000 = 20 Ás
We are not talking about a delay bellow ms here. Admittedly we must provide a clear quantitative estimation but there is no question that the difference in overshoot is due to way higher than 1ms delay in rise (and fall) times.

Quote
The fact that there is a sudden rise and fall when rf is on and off is enough.

That is what the authors of the paper want to believe. And want us to believe. Don't believe, check. All those words are self-reassuring. If those differences in overshoot are inconsequential then it is not a waste of time to show how and why they are inconsequential. In my eye they are not inconsequential, so I will check, and see that there is a difference in rise time, and that the thruster is not "an instant on/off device", as you admit yourself. And there maybe we wont agree on the fact that it is consequential that the thruster takes 100ms to reach it's plateau. There is enough information in those curves to falsify all electromagnetic "propellentless" explanations.
« Last Edit: 11/10/2014 10:17 AM by frobnicat »

Online RotoSequence

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Re: EM Drive Developments
« Reply #3084 on: 11/10/2014 10:13 AM »
Well it does take time for energy to build up in the cavity.

Yes it does. On the order of Q * typical_length / c = 20000 * .3 / 300000000 = 20 Ás
We are not talking about a delay bellow ms here. Admittedly we must provide a clear quantitative estimation but there is no question that the difference in overshoot is due to way higher than 1ms delay in rise (and fall) times.

For clarity's sake, you're saying that the impulse delays could be caused by the amplifier warming up, and the undershoot at lower power levels, rather than higher level ones, is evidence of that?

Offline frobnicat

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Re: EM Drive Developments
« Reply #3085 on: 11/10/2014 10:27 AM »
Well it does take time for energy to build up in the cavity.

Yes it does. On the order of Q * typical_length / c = 20000 * .3 / 300000000 = 20 Ás
We are not talking about a delay bellow ms here. Admittedly we must provide a clear quantitative estimation but there is no question that the difference in overshoot is due to way higher than 1ms delay in rise (and fall) times.

For clarity's sake, you're saying that the impulse delays could be caused by the amplifier warming up, and the undershoot at lower power levels, rather than higher level ones, is evidence of that?

The "undershoot" signature appears to occur more for the low power experiment (at 2.6 W) than for the higher power (around 16.8W) :

- This would be a natural parameter dependency for a thermal effect.
Meaning the thermal artefacts (be it at the place of the amplifier or the thruster) takes longer to reach a plateau at lower powers, so that thermal explanations are in good qualitative agreement.

- while it would be a very contrived consequence of an amplifier power-on delay
Meaning that if we had a real effect, with no delays, but the microwave power was fed to the thruster in a less than ideal way because the amplifier takes some time to reach nominal power (because of charging capacitors in the first stages for instance), then it becomes very hard to see why it would take longer time to reach a plateau of lower power (for the amplifier).

Avoid talking about "warming-up" of the amplifier because it risks confusion of the two different things.

Offline Mulletron

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Re: EM Drive Developments
« Reply #3086 on: 11/10/2014 10:31 AM »
I'm saying, that you're basing all this on a cal pulse produced from a system from which you know very little. You don't know how much power it is capable of delivering to the fins 1, and you don't know the mass of the test rig 2.

You're assuming that the designers of the experiment intended for the rise and falls to be the same between the test article and the cal system. Why? I don't know. The force delivered to the LDS by the cal system and the test article are from two different kinds of devices. So the only thing in common is quantitatively they each deliver a force to be measured. The kinematics of how that force is provided is different.

Cal system: Voltage applied to fins (power?), pretty much instant impulse (sharp rise), result measured slowed by inertia of test rig.

Test article: Rf building up in cavity, slower to respond impulse (still sharp rise), result measured slowed by same inertia of test rig.

We can calculate all day how long it takes for energy to build up in the cavity/q but it is inconsequential. Doesn't help. It's been done on this forum. You can't even see microseconds on the graph.

Quote
The "undershoot" signature appears to occur more for the low power experiment (at 2.6 W) than for the higher power (around 16.8W) :

- This would be a natural parameter dependency for a thermal effect.
Meaning the thermal artefacts (be it at the place of the amplifier or the thruster) takes longer to reach a plateau at lower powers, so that thermal explanations are in good qualitative agreement.

Well I'm on board qualitatively with thermal effects. There ARE thermal effects. No issues here. You can see thermal effects with every gentle slope.......Electromagnetic artifacts create sharply rising slopes.

As far as the bolded quote above. There is no more or less overshoot happening across the tests. Attached is a screen shot that shows the test article bounces more, less, and close to equally to the same bounce from the cal pulse. The important take away is that there is always a bounce and that the bounces are consistent.

You're in France right? I'm in Italy (not Italian though). We're up arguing before the rest of the group wakes up.
« Last Edit: 11/10/2014 11:20 AM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3087 on: 11/10/2014 11:15 AM »
1) It is incorrect to state that we don't know the mass on the inverted torsional pendulum.  Paul March gave us the mass.

2) The natural frequency of the inverted torsional pendulum is dependent on the mass on the pendulum.

3) The natural frequency of the inverted torsional pendulum can be extracted by Fourier Transform of the data, as we did, and it checks. 

4) Paul March also gave us the natural frequency of the inverted pendulum, and it checks with the above information.

5) Paul March also informed us that the mass and its positional arrangement on the inverted pendulum did not change from test to test.

6) If the mass, moment of inertia and stiffness didn't change from test to test, then the natural frequency should not change from test to test.  The fact that it didn't change is confirmed by the Fourier Transform of the data.
« Last Edit: 11/10/2014 11:58 AM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3088 on: 11/10/2014 11:39 AM »
Quote
1) Someone is stating that we don't know the mass on the inverted torsional pendulum.  This is an incorrect statement.  Paul March gave us the mass.

Well I really need the mass of the test articles. The mass of the pendulum and the test articles would be so useful. Was that provided?

You see, if I had the mass of the test article, I could work out all the other math, like Delta V and put a check on that specific impulse I found.
« Last Edit: 11/10/2014 11:50 AM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3089 on: 11/10/2014 12:05 PM »
Quote
1) Someone is stating that we don't know the mass on the inverted torsional pendulum.  This is an incorrect statement.  Paul March gave us the mass.

Well I really need the mass of the test articles. The mass of the pendulum and the test articles would be so useful. Was that provided?

You see, if I had the mass of the test article, I could work out all the other math, like Delta V and put a check on that specific impulse I found.

25 pound total load on the torque pendulum arm

Offline Mulletron

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Re: EM Drive Developments
« Reply #3090 on: 11/10/2014 12:18 PM »
Yes the comments from 22 October say that is the MAX supportable load on the arm:

http://forum.nasaspaceflight.com/index.php?topic=29276.msg1275117#msg1275117
Quote
"And I just verified that Paul March wrote that the supported mass was a maximum of 25 lbm.  That is 11.3398 kgm"

That came from here:

http://nextbigfuture.com/2014/09/paul-march-is-providing-more.html

"Each bearing block is rated for ~25.0 Lb of vertical mass load, so we nominally restrict ourselves to a 25 pound total load limit on the torque pendulum arm to give ourselves a 100% support mass margin."

Ok so it can hold 25 pounds......But what are the actual masses of the test articles or the pendulum?
« Last Edit: 11/10/2014 12:19 PM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3091 on: 11/10/2014 12:33 PM »
1) Paul March posted the information in this  NASASpaceFlight.com forum and not in the Next big future webpage.  Next big future just copied the information from this forum into their webpage.  They recognized this by stating at the outset:  "Paul March ... is providing information about the experiments on the NASA spaceflight forum." There is no need to give any credit to Next Big Future, on the contrary, it is Next Big Future that owes credit to NASASpaceFlight.com and to Paul March.  NASASpaceFlight forum is the true source of this mass information.

2) I do not recall information for mass of individual items.  The total mass, dimensions and stiffness is what is required for the lowest natural frequency of the pendulum.   Individual motion of items on the pendulum can only occur at much higher frequencies (and lower amplitudes) than the lowest natural frequency of the pendulum
« Last Edit: 11/10/2014 12:40 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3092 on: 11/10/2014 12:42 PM »
1) Paul March posted the information in this  NASASpaceFlight.com forum and not in the Next big future webpage.  Next big future just copied the information from this forum into their webpage.  They recognized this by stating at the outset:  "Paul March ... is providing information about the experiments on the NASA spaceflight forum." There is no need to give any credit to Next Big Future, on the contrary, it is Next Big Future that owes credit to NASASpaceFlight.com and to Paul March.  NASASpaceFlight forum is the true source of this mass information.

2) I do not recall information for mass of individual items.  The total mass, dimensions and stiffness is what is required for the lowest natural frequency of the pendulum.   Individual motion of items on the pendulum can only occur at much higher frequencies (and lower amplitudes) than the lowest natural frequency of the pendulum

Are you using that 25lb figure as total mass? Because that is just how much weight it can hold. That isn't the mass of anything.
« Last Edit: 11/10/2014 12:43 PM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3093 on: 11/10/2014 12:54 PM »
1) Paul March posted the information in this  NASASpaceFlight.com forum and not in the Next big future webpage.  Next big future just copied the information from this forum into their webpage.  They recognized this by stating at the outset:  "Paul March ... is providing information about the experiments on the NASA spaceflight forum." There is no need to give any credit to Next Big Future, on the contrary, it is Next Big Future that owes credit to NASASpaceFlight.com and to Paul March.  NASASpaceFlight forum is the true source of this mass information.

2) I do not recall information for mass of individual items.  The total mass, dimensions and stiffness is what is required for the lowest natural frequency of the pendulum.   Individual motion of items on the pendulum can only occur at much higher frequencies (and lower amplitudes) than the lowest natural frequency of the pendulum

Are you using that 25lb figure as total mass? Because that is just how much weight it can hold. That isn't the mass of anything.

For context and meaning read the original statements from Paul March in NASASpaceFlightForum instead of referring to NextBigFuture. 

Paul March stated: 

Quote
we nominally restrict ourselves to a 25 pound total load limit on the torque pendulum arm

This total mass (25 lb) checks with the natural frequency provided by Paul March and with the natural frequency obtained by Fourier Transform of the data.  A lower total mass than 25 lb leads to higher natural frequencies, since the natural frequency is proportional to the inverse square root of the total mass.

And how much lower than 25 lb do you think that the total mass on the pendulum would be and why?

Were you to claim that the total mass would be be 12 lb for example, the natural frequency would be 44% higher.  Were you to claim that the total mass would be 2.5 lbs the natural frequency would be 3 times higher.  Do you really think that the total mass on the pendulum is only 2.5 lbs ?  How would that agree with common sense (you were posting to Frobnicat to use common sense previously and now you are questioning that the total mass on the pendulum can be orders of magnitude lower than 25 lbs?)
« Last Edit: 11/10/2014 01:15 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3094 on: 11/10/2014 01:15 PM »
This quote:

Quote
we nominally restrict ourselves to a 25 pound total load limit on the torque pendulum arm

is from NBF dated 11Sep14.

Where is it on here from March for sake of clarity?

Your comments:

http://forum.nasaspaceflight.com/index.php?topic=29276.msg1275117#msg1275117

22Oct14.

Indeed NBF references NSF, but it is about electrical issues. First linked to. But they have slides from March which contain the mechanical data, which weren't posted here.
http://forum.nasaspaceflight.com/index.php?topic=29276.msg1254155#msg1254155

I don't want to start a war over this, but I remain correct when I asserted that we don't know the mass of the things inside the test chamber. So how can we blindly throw numbers at them? We can't just say 25lb/11.34kg based off of the max weight it can hold.

I'm not the first to comment on here about blindly throwing numbers at assumptions. It ends up being a waste of time and sends everyone on a tangent based on bad info.

Quote
And how much lower than 25 lb do you think that the total mass on the pendulum would be and why?

There is no "think" about this, just what the mass actually really is.

You can't pass off quantitative results derived from qualitative data.


All you can ethically do is make rough approximations, based on the lack of data which is available; which is what I do around here most of the time......and for good reason.

Nuff said.
« Last Edit: 11/11/2014 01:03 AM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3095 on: 11/10/2014 01:23 PM »
This quote:

Quote
we nominally restrict ourselves to a 25 pound total load limit on the torque pendulum arm

is from NBF dated 11Sep14.

Where is it on here from March for sake of clarity?

Your comments:

http://forum.nasaspaceflight.com/index.php?topic=29276.msg1275117#msg1275117

22Oct14.

Indeed NBF references NSF, but it is about electrical issues. First linked to. But they have slides from March which contain the mechanical data, which weren't posted here.

I don't want to start a war over this, but I remain correct when I asserted that we don't know the mass of the things inside the test chamber. So how can we blindly throw numbers at them? We can't just say 25lb/11.34kg based off of the max weight it can hold.

I'm not the first to comment on here about blindly throwing numbers at assumptions. It ends up being a waste of time and sends everyone on a tangent based on bad info.

Quote
And how much lower than 25 lb do you think that the total mass on the pendulum would be and why?

There is no "think" about this, just what the mass actually really is.

You can't pass off quantitative results derived from qualitative data.

You sermonize to Frobnicat about using common sense and now you maintain that the total load on the pendulum could be 2 lb instead of 25 lb?  I don't think that common sense says that the total mass could be 2 lb

What it looks to me is that you overlooked the fact that natural frequencies are weakly dependent on mass (it goes like the square root of mass), so that small changes in mass make a much smaller difference to the natural frequency.   

Just admit it.
« Last Edit: 11/10/2014 01:27 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3096 on: 11/10/2014 01:29 PM »
We don't know the mass. That is the point. I'm not being a meanie or a negative nancy. I'm sticking to the facts. I'm being practical.

The methodology you describe is like guessing how massive my truck is based on its cargo capacity.
And then running with that number.

If you had the data, you'd be right.

I'm finished here.
« Last Edit: 11/10/2014 01:33 PM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3097 on: 11/10/2014 01:30 PM »
We don't know the mass. That is the point. I don't mean to be mean. I'm sticking to the facts.

The methodology you describe is like guessing how massive my truck is based on its cargo capacity.

If you had the data, you'd be right.

I'm finished here.

Does common sense (see attached picture) show that the total mass on the pendulum could be a few ounces instead of ~<25 lb ?

Do you understand that small changes in total mass do not affect the natural frequency very much because the natural frequency goes like the square root of the mass? 

A 10% change in mass makes only a 5% difference in natural frequency.
A 20% change in mass makes only a 10% difference in natural frequency.

Do you understand that we have the time response and that one can obtain the natural frequency by performing a Fourier Transform of the response without having any knowledge of the mass?  (that's what we also have here and you neglected to mention in the truck example)
« Last Edit: 11/10/2014 02:01 PM by Rodal »

Offline Mulletron

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Re: EM Drive Developments
« Reply #3098 on: 11/10/2014 02:01 PM »
I don't care about the pendulum frequency. The amplitudes are important. The force required to move a pendulum of x mass (in the first place) varies wildly depending on mass. The kinetic energy and potential energy of a moving pendulum varies wildly depending on the mass of the pendulum as well.

None of my screen shots previously, pointing out the "bounce" had anything to do with frequency, but the amplitudes were different.

Here's something for the folks out there to play with. Take 2 pendulums, give them wildly different masses. Set them in opposite motion. Timing is everything......You'll see frequency is unaffected by mass, yet PE and KE are. Also getting the pendulum to move in the first place is very much dependent on mass. F=MA as they say.
Let your computer do the work for you.....

This author never made any assertions of the mass of anything. Simply we don't know the masses of anything.

http://phet.colorado.edu/sims/pendulum-lab/pendulum-lab_en.html
« Last Edit: 11/10/2014 02:03 PM by Mulletron »
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Online Rodal

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Re: EM Drive Developments
« Reply #3099 on: 11/10/2014 02:08 PM »
I don't care about the pendulum frequency. The amplitudes are important. The force required to move a pendulum of x mass (in the first place) varies wildly depending on mass. The kinetic energy and potential energy of a moving pendulum varies wildly depending on the mass of the pendulum as well.

None of my screen shots previously, pointing out the "bounce" had anything to do with frequency, but the amplitudes were different.

Here's something for the folks out there to play with. Take 2 pendulums, give them wildly different masses. Set them in opposite motion. Timing is everything......You'll see frequency is unaffected by mass, yet PE and KE are. Also getting the pendulum to move in the first place is very much dependent on mass. F=MA as they say.
Let your computer do the work for you.....

This author never made any assertions of the mass of anything. Simply we don't know the masses of anything.

http://phet.colorado.edu/sims/pendulum-lab/pendulum-lab_en.html

Wrong!

The transient amplitude of the torsional pendulum is dictated by the static deflection (the ratio of the applied force to the stiffness) and most importantly by the ratio of the exciting frequency to the natural frequency of the system !

You are arguing about the dynamics and you write that you "don't care about the pendulum frequency" ?

The magnitude of the transient response which results from an impulse depends on the ratio of the impulsive load duration to the inverse of the natural frequency (the natural period).

The "folks" here know that the equation is not F=ma=m d2x/dt2, it is

m d2x/dt2 +c dx/dt + k x = F(t)

The "folks" here know that the response of this system depends on the natural frequency !


« Last Edit: 11/10/2014 02:53 PM by Rodal »

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