Experiment to test F=ma

[Yaniv]

According to physics weight=mass*gravity.

Since mass and gravity are constants weight must be a constant too.

I searched the literature and found several papers (Glaser, 1990; Dmitriev, 2003) showing weights of heated metals decrease at increasing temperatures. Glaser says air convection is responsible for weight reduction but Dmitriev weight reduction of a heated thermal insulator cast doubt on Glaser's explanation. Surely not conclusive.

I propose an experiment to test this; weigh a heated metal in vacuum.

If weight decreases at increasing temperatures in vacuum, as my theory predicts, F=ma is disproved.

Interested to do the experiment ?

 

 

[DrRocket]

According to physics weight=mass*gravity.

Since mass and gravity are constants weight must be a constant too.

I searched the literature and found several papers (Glaser, 1990; Dmitriev, 2003) showing weights of heated metals decrease at increasing temperatures. Glaser says air convection is responsible for weight reduction but Dmitriev weight reduction of a heated thermal insulator cast doubt on Glaser's explanation. Surely not conclusive.

I propose an experiment to test this; weigh a heated metal in vacuum.

If weight decreases at increasing temperatures in vacuum, as my theory predicts, F=ma is disproved.

Interested to do the experiment ?

 

 

 

There is actually, due to relativity, a slight increase in invariant mass with an increase in temperature.

 

At normal speeds and temperatures F=ma has a mountain of experimental support.

 

Your "theory" is groundless.

[Yaniv]

You say weight should increase a tiny bit at incresing temperatures.

I heard that many times but the experimental results show to the contrary.

Maybe your prediction is wrong ?

[ajb]

It sounds to me that one will have to be very careful when examining the experiments as to not confuse "fundamental results" and "secondary effect". One would expect, as DrRocket has said a very small increase in the measured mass due to [math]E = mc^{2}[/math]. However, this could easily be swamped by other effects as you suggest.

 

I expect that any experimental measurement of the mass decreasing would be due to effects on the apparatus, like convection currents or thermal expansion or something.

 

Unless it is real, this would be something not expected and interesting.

 

I do not really see how this tests Newton's F=ma.

[Schrödinger's hat]

There is actually, due to relativity, a slight increase in invariant mass with an increase in temperature.

 

At normal speeds and temperatures F=ma has a mountain of experimental support.

This effect would be miniscule.

Wouldn't one have to take radiation pressure of the reflected IR from whatever it was resting on into account by the time you get to these scales?

[Yaniv]

Weighing a heated metal in VACUUM eliminates air related influences such as bouyancy and heat convection.

W=mg is like F=ma. You can not have two constants on one side of the equation and a variable on the other ? If weight changes at different temperatures, then weight is a variable.

[John Cuthber]

I have an idea.

Lets get someone else to pay for the experiment.

Let's use some bits of metal in a vacuum that someone has already paid for.

In particular, lets use the GPS satellites.

Now, when they are in the shadow of the earth they cool down and when they are in sunlight they heat up.

If their weight changed it would affect their orbit and they would give the "wrong" answers for people using them for navigation.

They don't, or at least, if they do the effect it tiny.

It was a nice theory while it lasted.

 

Incidentally, gravity isn't a constant, for example it's about 6 times less on the moon.

A good analytical balance will let you measure the difference in gravity between the top and bottom of a tall building.

 

So this bit "You can not have two constants on one side of the equation and a variable on the other " doesn't make sense.

[Yaniv]

A good balance in the lab, set on a fixed position, experiences constant gravity.

 

Doing the experiment in the lab is better because your metal is not in motion. Why complicate things.

Start with the simplest experiment please.

[swansont]

Metals still have a vapor pressure you will lose atoms faster if you heat the metal, but this will still be a very small effect.

 

But I don't see how this necessarily measures F=ma. Might a violation be chalked up to a violation of the equivalence principle?

 

A good balance in the lab, set on a fixed position, experiences constant gravity.

 

Doing the experiment in the lab is better because your metal is not in motion. Why complicate things.

Start with the simplest experiment please.

Earth tides make "fixed position" moot.

[Yaniv]

Metals still have a vapor pressure you will lose atoms faster if you heat the metal, but this will still be a very small effect.

 

A Dmitriev graph shows that when a heated metal is cooled its weight begins to go back to pre-heating weight and Glaser's cooled metals recorded increasing weights so vaporisation is unlikely and could be easily tested.

 

But I don't see how this necessarily measures F=ma. Might a violation be chalked up to a violation of the equivalence principle?

 

If weight changes at increasing temperatures, either the first constant of physics (mass) or the second constant of physics (gravity), or both, are not constants. This is surely more fundamental than the seventh or so constant of physics - speed of light.

 

Earth tides make "fixed position" moot.

The heating process should last a few minutes so the position of the moon is likely negligable.

 

Why find so many excuses NOT to do the experiment ?

[swansont]

Why find so many excuses NOT to do the experiment ?

The effect you seek is small, if it exists. It's a very hard experiment to do. People have been explaining the barriers to doing it properly.

[rktpro]

As far as my knowledge go, a metal expands on heating. Heating just increases the volume of the metal not the mass. g is constant to particular area only. It varies at poles and equator too.

[Yaniv]

How to eliminate ''noise'' from the experiment ?

 

Set up the apparatus. Place a balance, heat source and a thermometer inside a vacuum chamber and set the electronics for external control. Insulate the balance and use a thermostat to keep balance at a constant temperature as possible to reduce ''noise''. Next, place the metal beside the balance and heat the chamber to a fixed duration to a known temperature. The change in weight you get is your ''noise''. Next, place the metal on the balance and repeat the heating process. Do you get a different reading ?

 

Come on guys, it's not a rocket science.

 

 

[swansont]

How to eliminate ''noise'' from the experiment ?

 

Set up the apparatus. Place a balance, heat source and a thermometer inside a vacuum chamber and set the electronics for external control. Insulate the balance and use a thermostat to keep balance at a constant temperature as possible to reduce ''noise''. Next, place the metal beside the balance and heat the chamber to a fixed duration to a known temperature. The change in weight you get is your ''noise''. Next, place the metal on the balance and repeat the heating process. Do you get a different reading ?

 

Come on guys, it's not a rocket science.

 

How big of an effect do you expect to see? Compare this to how precise scales are. Now compare it to the precision of other gravity experiments.

[Yaniv]

Glaser paper describes 20 grams metal rod heated by 5 degC lost 100 micrograms. Air convection likely to contribute so lost likely to be even smaller. Modern precision balances measure down to single micrograms (with standard error of a couple of micrograms) and should pick up changes of just a few micrograms.

 

The question now is not how many micrograms to expect. Any measurable change will do. The experiment should be carried out with the highest precision achivable by the experimentalist.

[imatfaal]

100 micrograms is enormous ! Do you have a link to the paper?

[DrRocket]

This effect would be miniscule.

Wouldn't one have to take radiation pressure of the reflected IR from whatever it was resting on into account by the time you get to these scales?

 

At normal speeds and temperatures all of the effects under discussion would be miniscule. Direct measurement would need to consider any number of subtle effects, many dependent on yhe precise nature of the hardware involved. Nevertheless, in principle, relativity shows that invariant mass increases with increasing temperature.

 

To actually perform such an experiment would require a very ingeneous experimental physicist. But ingenuity is the stock in trade of experimentalists. Take a look at the thread on the reported superluminal neutrinos for an example of how subtle and ingeneous some experiments really are, and how difficult and sophisticated the resulting data analysis can become -- that experiment is still very much preliminary and under review.

[Yaniv]

Google "Response of Apparent Mass to Thermal Gradients" or go to M Glaser 1990 Metrologia 27.

[swansont]

Google "Response of Apparent Mass to Thermal Gradients" or go to M Glaser 1990 Metrologia 27.

"The change of the apparent mass of 20-g masses and tubes that are not in thermal equilibrium with ambient air has been observed. Buoyancy, adsorption and convection influences are discussed. Quantitative comparisons show that, under such conditions, it is predominantly free convection forces which change the apparent mass."

 

Doesn't sound like any change in actual mass was observed.

[Yaniv]

"The change of the apparent mass of 20-g masses and tubes that are not in thermal equilibrium with ambient air has been observed. Buoyancy, adsorption and convection influences are discussed. Quantitative comparisons show that, under such conditions, it is predominantly free convection forces which change the apparent mass."

 

Doesn't sound like any change in actual mass was observed.

 

Glaser conclusion is based on the untested assumption that weight does NOT change at increasing temperatures in vacuum. How can he say this when the "control experiment" is missing from the paper ?

[John Cuthber]

You seem not to have understood my post.

The experiment has been done.

The pieces of metal were the GPS satellites.

The result is quite simple; your theory is wrong.

If there were changes of anything like that magnitude (something like 5 ppm) the effect would show up as noticeable errors in the GPS measurements.

 

Your theory has been tested.

It failed.

You can stop now and go and do something else.

Edited October 8, 2011 by John Cuthber

[Yaniv]

My theory predicts hot and cold objects should fall at the same rate.

Google "Magnetic Universe Theory of Science" to check it out.

Please do the experiment I propose and don't confuse experiments.

 

 

 

[John Cuthber]

The experiment has been done countless times.

If the effect you predict was real then the people who make this sort of kit

http://www.netzsch-thermal-analysis.com/en/products/thermobalances/

would have noticed.

Are you accusing them of incompetency?

[swansont]

Your claim boils down to inertial mass and gravitational mass being different. How about researching the literature first, before claiming that experiments haven't been done.

[Yaniv]

I am not familiar with the machine. Maybe the computer compensate for weight as a function of temperature ?

 

Send me results and I will drop my theory. But don't ask me to drop my theory without the results.