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Author Topic: Do we need acceleration to define the concept of mass?  (Read 16324 times)

Offline imatfaal

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Re: Do we need acceleration to define the concept of mass?
« Reply #50 on: 11/06/2012 13:39:41 »
1) The increase in heat of the water is equivalent to the loss of mass.  So presumably you are referring to the equivalence principle E=mc2.  The 2 in c2 represents acceleration.
velocity squared DNE acceleration
Quote
2) The energy produced is unknown until it is measured which involves obliterating the photons making them give up their energy as momentum and re-radiating some photons at a lower energy level.  The increase in momentum of the target is acceleration.
E = h.nu

Quote
3) Presumably this relies upon knowing initially both the volume and mass of 1 molecule.
Knowing the mass of 1 molecule relies upon counting the total number of protons and neutrons and knowing the weight of a proton.
“Because atoms are exceptionally small, scientists typically work with atoms in larger quantities called moles. A mole is the amount of a substance with as many atoms as there would be in 12 grams of the isotope carbon-12. This number is roughly 600 sextillion (6 times 10 to the 23rd power) atoms, and is known as Avogadro's number for the scientist who defined it.”
http://www.wikihow.com/Calculate-Atomic-Mass

This method of calculating the mass depends upon initially knowing the atomic weight of one molecule and that requires ‘weighing’ it.  Weighing it requires a non-inertial (accelerating) reference frame.  It’s a calculation based upon a measurement taken in an accelerating reference frame.
  volume of molecule no need to know.  mass of molecule is calculable as well as measurable
 
Quote
4) Is essentially the same answer as 3 but substituting atom for molecule.
  i never mentioned molecule btw.  And three is easily done - whereas 4 is v difficult
 

Offline Geezer

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Re: Do we need acceleration to define the concept of mass?
« Reply #51 on: 11/06/2012 19:59:05 »

It's not arbitrary as it is comparing an unknown mass with a known mass.

All three cases involve acceleration and acceleration costs energy.  In the case of the spring and triple balance the energy comes from gravitational potential energy.  It makes little difference where the energy comes from it still causes acceleration and gives "some idea of the relationship between mass and energy".

As Evan points out, the known mass is completely arbitrary, so the compared mass is also completely arbitrary. Consequently, any form of balance isn't really telling you anything about the mass.

If you use a spring type scale, or an accelerometer, you are determining weight, not mass. You could use a "known mass" to determine the intensity of a gravitational field by this method then do a comparison to determine the relative mass of another object, but then you are back to only establishing a comparitive arbitrary mass.

On the other hand, if you actually alter the momentum of an object, there are methods of directly quantifying the energy conversion.




I agree it does not tell you anything about mass itself but it is not really arbitrary if you do the comparison with a known mass. Anyway that argument is beside the point.

The question was “Do we need acceleration to define the concept of mass?"

How do you propose to "alter the momentum of an object" without accelerating it?

If you accept that it accelerates then presumably you accept that you "Do .. need acceleration to define the concept of mass?" Which is what I said in the first place and repeated in post #40 of this thread.
"For example imagine a big rock floating in space. Give it a slap with a calibrated hand so you know exactly how much energy you gave it. Now measure how fast the rock is moving."
http://education.jlab.org/qa/mass_01.html
"That's one way of measuring the mass and it involved acceleration of the mass."

Actually, that's what I've saying all along. Please refer to Reply #2 on this thread.

My original objection was to your statement about "acceleration in space-time" which is completely irrelevant. You then you introduced "gravitational acceleration" which I have repeatedly demonstrated will only let you weigh an object, or at best, compare the relative masses of two objects.
 

Offline Geezer

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Re: Do we need acceleration to define the concept of mass?
« Reply #52 on: 11/06/2012 21:18:32 »

The Earth pushes the scale.  The scale pushes the mass.  This results in a change of momentum for the mass.  This is acceleration.


Sorry, but that's not right either.  The only change in momentum is caused by the rotation of the Earth and the rotation of the object, and the amount of the change is very small.

Quote
A tripple balance compares an unknown mass with a known mass and the difference in gravity (acceleration) on different planets is compensated for by affecting both the known and unknown mass in the same proportion.  The mass remains the same but the weight changes.

Yes, mass is constant, but you are ignoring the fact that gravity on Earth is not constant, so the weight of an object on Earth varies with location.

Quote
Whether you apply acceleration to the mass by the Earth pushing it or anything else pushing it, its the same thing, acceleration.

Pushing is NOT the same as acceleration. Acceleration requires a change in velocity. In Classical Mechanics, gravity produces an accelerative force that acts on all matter, but there is only acceleration with change in velocity, hence a change in momentum.

Quote
There is no difference between accelerating a mass by applying a force to it and the Earth accelerating the same mass by applying a pseudo-force to it (gravity).  They are equivalent.

But the object is not accelerating. Your argument only applies if you allow the object to free-fall, but then you will find that all objects accelerate at the same rate regardless of their mass. Treating gravity as a pseudo-force only works if you apply General Relativity. That means you have to analyze the entire problem using General Relativity.

Quote
There is no difference in measuring a force applied to a mass and the distance it travels than measuring the pseudo-force the Earth applies to the same mass and the distance it travels.

Except that you don't know what the gravitational force actually is, and there isn't any "travel".
 

Offline MikeS

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Re: Do we need acceleration to define the concept of mass?
« Reply #53 on: 12/06/2012 07:39:43 »

The Earth pushes the scale.  The scale pushes the mass.  This results in a change of momentum for the mass.  This is acceleration.


Sorry, but that's not right either.  The only change in momentum is caused by the rotation of the Earth and the rotation of the object, and the amount of the change is very small.

Quote
A tripple balance compares an unknown mass with a known mass and the difference in gravity (acceleration) on different planets is compensated for by affecting both the known and unknown mass in the same proportion.  The mass remains the same but the weight changes.

Yes, mass is constant, but you are ignoring the fact that gravity on Earth is not constant, so the weight of an object on Earth varies with location.

Quote
Whether you apply acceleration to the mass by the Earth pushing it or anything else pushing it, its the same thing, acceleration.

Pushing is NOT the same as acceleration. Acceleration requires a change in velocity. In Classical Mechanics, gravity produces an accelerative force that acts on all matter, but there is only acceleration with change in velocity, hence a change in momentum.

Quote
There is no difference between accelerating a mass by applying a force to it and the Earth accelerating the same mass by applying a pseudo-force to it (gravity).  They are equivalent.

But the object is not accelerating. Your argument only applies if you allow the object to free-fall, but then you will find that all objects accelerate at the same rate regardless of their mass. Treating gravity as a pseudo-force only works if you apply General Relativity. That means you have to analyze the entire problem using General Relativity.

Quote
There is no difference in measuring a force applied to a mass and the distance it travels than measuring the pseudo-force the Earth applies to the same mass and the distance it travels.



Except that you don't know what the gravitational force actually is, and there isn't any "travel".


That's not true.  According to Einstein, gravity and acceleration are equivalent.  It is the acceleration of the Earth that endows us with weight.

True but irrelevant to the discussion.

It is when talking about the acceleration of a massive body like the Earth.  A steady push is the steady application of energy.  The steady application of energy (as in a rocket for example) causes a steady acceleration.  A 'push' changes the velocity of the object.  That change in velocity is acceleration.

If you choose to ignore General Relativity then there is little point in discussing gravity.

We do know what the acceleration is it's 1 g.  There must be travel as the Earth is travelling through space-time.  Because we do not understand how to take the measurements does not make it any the less true.
« Last Edit: 12/06/2012 07:44:07 by MikeS »
 

Offline Geezer

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Re: Do we need acceleration to define the concept of mass?
« Reply #54 on: 12/06/2012 18:44:12 »

It is when talking about the acceleration of a massive body like the Earth.  A steady push is the steady application of energy.  The steady application of energy (as in a rocket for example) causes a steady acceleration.  A 'push' changes the velocity of the object.  That change in velocity is acceleration.

We do know what the acceleration is it's 1 g.  There must be travel as the Earth is travelling through space-time.  Because we do not understand how to take the measurements does not make it any the less true.


Mike, if you are going to argue using GR, I strongly suggest you study Classical Mechanics and basic Thermodynamics first. What you are suggesting here is that there is a continuous transfer of energy from the Earth to your backside when you are sitting in a chair. That is patently ridiculous. There is no change in energy of the Earth, you, or the chair, and even String Theory won't support the idea that there is.
 
 Standard Gravity on Earth is an approximation. It is not constant with location which is why weight varies depending on where you are on the Earth.
 

Offline imatfaal

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Re: Do we need acceleration to define the concept of mass?
« Reply #55 on: 13/06/2012 14:45:59 »
Mike - if you continue to promulgate your personal ideas of gravity/time/light etc in the main forums you will be suspended or banned.  Please do not continue this line of argument or theory anywhere other than in the New Theories.  Whilst we appreciate your enthusiasm we cannot tolerate the continued stream of mis-information and misguided posts; the next post in the main fora that you make that argues non-mainstream physics will lead to sanctions.

imatfaal \ moderator
 

Offline Vignesh

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Re: Do we need acceleration to define the concept of mass?
« Reply #56 on: 13/06/2012 14:52:25 »
Dude!  :)
Velocity and acceleration are interrelated... acceleration is nothing but the rate of change of velocity.. i.e., a=dv/dt
and also i would say, when an object's velocity or acceleration increases, thus the mass of the object indeed increases!  ;)
 

Offline Pmb

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Re: Do we need acceleration to define the concept of mass?
« Reply #57 on: 14/06/2012 00:29:13 »
mass is only a function of speed (magnitude of velocity), not of acceleration.
 

Offline MikeS

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Re: Do we need acceleration to define the concept of mass?
« Reply #58 on: 15/06/2012 10:00:42 »
1) The increase in heat of the water is equivalent to the loss of mass.  So presumably you are referring to the equivalence principle E=mc2.  The 2 in c2 represents acceleration.
velocity squared DNE acceleration
Quote
2) The energy produced is unknown until it is measured which involves obliterating the photons making them give up their energy as momentum and re-radiating some photons at a lower energy level.  The increase in momentum of the target is acceleration.
E = h.nu

Quote
3) Presumably this relies upon knowing initially both the volume and mass of 1 molecule.
Knowing the mass of 1 molecule relies upon counting the total number of protons and neutrons and knowing the weight of a proton.
“Because atoms are exceptionally small, scientists typically work with atoms in larger quantities called moles. A mole is the amount of a substance with as many atoms as there would be in 12 grams of the isotope carbon-12. This number is roughly 600 sextillion (6 times 10 to the 23rd power) atoms, and is known as Avogadro's number for the scientist who defined it.”
http://www.wikihow.com/Calculate-Atomic-Mass

This method of calculating the mass depends upon initially knowing the atomic weight of one molecule and that requires ‘weighing’ it.  Weighing it requires a non-inertial (accelerating) reference frame.  It’s a calculation based upon a measurement taken in an accelerating reference frame.
  volume of molecule no need to know.  mass of molecule is calculable as well as measurable
 
Quote
4) Is essentially the same answer as 3 but substituting atom for molecule.
  i never mentioned molecule btw.  And three is easily done - whereas 4 is v difficult


What does that mean?

To know the frequency or wavelength involves obliterating the photon which gives up its momentum by transferring it to something else.  That transfer involves a change in velocity which is acceleration.

How do you calculate it without first knowing the weight of either one molecule or constituent parts?  Weighing involves using a non-inertial (accelerating) reference frame.
 

Offline MikeS

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Re: Do we need acceleration to define the concept of mass?
« Reply #59 on: 15/06/2012 11:02:34 »

It is when talking about the acceleration of a massive body like the Earth.  A steady push is the steady application of energy.  The steady application of energy (as in a rocket for example) causes a steady acceleration.  A 'push' changes the velocity of the object.  That change in velocity is acceleration.

We do know what the acceleration is it's 1 g.  There must be travel as the Earth is travelling through space-time.  Because we do not understand how to take the measurements does not make it any the less true.


Mike, if you are going to argue using GR, I strongly suggest you study Classical Mechanics and basic Thermodynamics first. What you are suggesting here is that there is a continuous transfer of energy from the Earth to your backside when you are sitting in a chair. That is patently ridiculous. There is no change in energy of the Earth, you, or the chair, and even String Theory won't support the idea that there is.
 
 Standard Gravity on Earth is an approximation. It is not constant with location which is why weight varies depending on where you are on the Earth.

Is it ridiculous?  Let me see if I understand you correctly.  What you are saying is if You are sitting in a chair in a rocket accelerating at one g and approaching the speed of light you will not have gained mass?

My point was a push causes a change in velocity which involves acceleration. 

It costs the Earth nothing extra to accelerate anything on its surface (other than maybe meteorites) as everything is part of the Earths mass.

Whether or not the Earths acceleration in space-time (gravity) involves the expenditure or energy we simply do not know.  We do know that the Earth warps or bends space-time locally.  Maybe the Earth extracts energy from that. I am not postulating that it does, I am simply saying it remains a possibility until proven otherwise.
 

Offline MikeS

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Re: Do we need acceleration to define the concept of mass?
« Reply #60 on: 15/06/2012 11:12:29 »
mass is only a function of speed (magnitude of velocity), not of acceleration.

How does that relate to

quote lightarrow
 
Reply #2 on: 24/05/2012 21:52:40
Quote
"The best way is to consider the object...still 
An oject's mass is its energy (divided c2) when the object is still."


and
The question was not about what mass is a function of but "Do we need acceleration to define the concept of mass?"
« Last Edit: 15/06/2012 11:14:41 by MikeS »
 

Offline MikeS

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Re: Do we need acceleration to define the concept of mass?
« Reply #61 on: 15/06/2012 13:39:18 »
Going back to basics and the original question

Do we need acceleration to define the concept of mass?

"The kilogram or kilogramme (SI symbol: kg), also known as the kilo, is the base unit of mass in the International System of Units and is defined as being equal to the mass of the International Prototype Kilogram (IPK), which is almost exactly equal to the mass of one liter of water."

The IPK is made of a platinum–iridium alloy and is stored in a vault at the International Bureau of Weights and Measures in Sèvres, France.  It is known as Le Grand K.
http://en.wikipedia.org/wiki/Kilogram

The kilogram is by definition what the IPK weighs and is not a constant in the sense that the speed of light is a constant.

Weight
From Wikipedia, the free encyclopedia

"A spring scale measures the weight of an object (according to the operational definition)

In science and engineering, the weight of an object is the force on the object due to gravity.[2][3] Its magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g;[4] thus: W = mg. When considered a vector, weight is often denoted by a bold letter W. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton. For example, an object with a mass of one kilogram has a weight of about 9.8 newtons on the surface of the Earth, about one-sixth as much on the Moon, and very nearly zero when in deep space far away from all bodies imparting gravitational influence."

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

The Newton
"Definition

The newton is the SI unit for force; it is equal to the amount of net force required to accelerate a mass of one kilogram at a rate of one metre per second squared. Newton's second law of motion states: F = ma, multiplying m (kg) by a (m/s2), The newton is therefore:[1]

N=kg x m/s2

Units used:
N = newton
kg = kilogram
m = metre
s = second

http://en.wikipedia.org/wiki/Newton_(unit)

“Le Grand K has been losing weight — or, by the definition of mass under the metric system, the rest of the universe has been getting fatter. The most recent comparison, in 1988, found a discrepancy as large as five-hundredths of a milligram, a bit less than the weight of a dust speck, between Le Grand K and its official underlings.

This state of affairs is intolerable to the guardians of weights and measures. “Something must be done,” says Terry Quinn, director emeritus of the International Bureau of Weights and Measures, the governing body of the metric system. Since the early 1990s, Quinn has campaigned to redefine the kilogram based not on a physical prototype but on a constant of nature, something hardwired into the circuitry of the universe. In fact, of the seven fundamental metric units — the kilogram, meter, second, ampere, kelvin, mole, and candela — only the kilogram is still dependent on a physical artifact. (The meter, for example, was redefined 30 years ago as the distance traveled by light in a given fraction of a second.)”

http://www.wired.com/magazine/2011/09/ff_kilogram/all/1

What is the point of the above?  The point is the "The kilogram or kilogramme (SI symbol: kg), also known as the kilo, is the base unit of mass in the International System of Units” is defined by measuring its acceleration (weighing it). “Its magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g;[4] thus: W = mg.”  “ The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton.”   “The newton is the SI unit for force; it is equal to the amount of net force required to accelerate a mass of one kilogram at a rate of one metre per second squared.”  “In science and engineering, the weight of an object is the force on the object due to gravity.[2][3] Its magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g;[4] thus: W = mg.”  So, going back to the original question “Do we need acceleration to define the concept of mass?”  From the above it is obvious that we do.

As Le Grand K has been loosing weight in comparison to the rest of the Universe it is necessary to find a way of defining mass by using some constant of nature as opposed to using an artifact.  “So two decades ago, as Quinn’s campaign to switch the kilo to a physical constant began to gain traction, Becker and his colleagues decided to tackle the problem from the opposite direction. Building upon their earlier work, they decided to create a 1-kilogram sphere, not from hydrogen, but from silicon. The sphere would be identical in mass to the international prototype. Then, because Becker’s x-ray experiments had shown that the atoms were arranged in a regular pattern, they could use basic geometry to deduce how many silicon atoms the crystalline sphere contained. Once the number of atoms was determined with sufficient precision, that figure would forever define the mass of the kilogram. In other words, they set out to make a new artifact superior to Le Grand K — but only so that they could count its atoms and then eliminate all kilogram artifacts in perpetuity.”

The other approach is to use an apparatus called a watt balance, which compares electrical and mechanical power.  “On the upper floor is a room-sized scale dominated by a wheel fabricated of milled aluminum. Below the wheel is a hand-sized pan supporting a platinum-iridium mass positioned like an apple on a produce scale. One floor below, superconducting electromagnets counteract the downward tug of the platinum-iridium. In other words, the gravitational force on the mass is balanced with the electrical force produced by current in the copper coil. Once calibrated against the international prototype, the electronic kilogram can be defined in terms of the voltage required to levitate Le Grand K — a numerical value, governed by a natural constant, that can be used to calibrate any future watt balance — and the international prototype can at last be sent into retirement.” 
http://www.wired.com/magazine/2011/09/ff_kilogram/all/1

Both of the above alternatives of defining a kg of mass require weighing the object.  In the first case knowing the weight of a silicon atom and counting (calculating) the number of atoms.  In the second case weighing the object by knowing the amount of energy required to levitate it.  Both scenarios require weighing the object and that requires the use of a non-inertial (accelerating) reference frame.


 

Offline JP

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Re: Do we need acceleration to define the concept of mass?
« Reply #62 on: 15/06/2012 16:02:57 »
Whether or not the Earths acceleration in space-time (gravity) involves the expenditure or energy we simply do not know.  We do know that the Earth warps or bends space-time locally.  Maybe the Earth extracts energy from that. I am not postulating that it does, I am simply saying it remains a possibility until proven otherwise.

Whether or not you're postulating your new theories or just stating them while not postulating them, I am postulating that you're banned for ignoring repeated moderator warnings to stop posting new theories in the mainstream fora.
 

Offline Pmb

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Re: Do we need acceleration to define the concept of mass?
« Reply #63 on: 15/06/2012 16:37:44 »
How does that relate to

quote lightarrow
 
Reply #2 on: 24/05/2012 21:52:40
Quote
"The best way is to consider the object...still 
An oject's mass is its energy (divided c2) when the object is still."


and
The question was not about what mass is a function of but "Do we need acceleration to define the concept of mass?"
Lightarrows comment works under certain situations. Under certain situations it fails, such as when a macroscopic body is under stress.

The inertia mass for a free point particle moving at speed v is

m = m_0/sqrt(1-(v/c)^2)

Notice that it depends only on v, not a = dv/dt. The acceleration could be arbitrarily high but if v = 0 m = m_0.
 

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Re: Do we need acceleration to define the concept of mass?
« Reply #63 on: 15/06/2012 16:37:44 »

 

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