From: bergervo@iae.nl
On 11/1/2018 9:53 PM, Sabbir Rahman wrote:
> On Thursday, November 1, 2018 at 11:30:04 AM UTC+3, Jos Bergervoet wrote:
>> On 10/31/2018 7:05 AM, Sabbir Rahman wrote:
>>> On Friday, August 17, 2018 at 10:07:39 AM UTC+3, Phillip Helbig (undress
to reply) wrote:
>>>> In article <2c0366cf-d2b2-4d5e-ad1b-47cd027030e5@googlegroups.com>,
>>>> writes:
>>>>
>>>>>> If you had two negative masses they would attract. Because with the
>>>>>> negative mass acceleration is towards a positive mass this experiment
>>>>>> may not be able to determine if antimatter is really negative mass.
>>>>
>>>> If I recall correctly, not long ago Steve Carlip pointed out here that
>>>> positive mass attracts everything, including negative mass, and negative
>>>> mass repels everything.
>>>
>>> I am a little bit late to join this thread (sorry), but I wanted to make a
>>> few important points.
>>>
>>> In general people have to be more specific when they refer to "negative
>>> mass". There are three mass types that enter into Newton's law of
>>> gravitation for example - inertial, active and passive mass. If the signs
of
>>> these three masses are I, A and P respectively, then the particle type can
>>> be specified by (I,A,P) - so there are 8 types, (+++), (++-), (+-+), (+--),
>>> (-++), (-+-), (--+) and (---). Obviously (+++) corresponds to ordinary
>>> matter and the remaining 7 have at least one kind of negative mass, so you
>>> need to be specific which type you mean. If you mean by negative mass type
>>> (---), which is the one allowed by the WEP, then this will indeed fall
>>> `downwards'. This type is also repels itself.
>>>
>>> Newton's law depends only on the product IP, so there are actually only 4
>>> types of particle in terms of mutual interactions.
>>
>> Why is that? In Newtons laws there is the force depending on:
>> 1 Mass creating the gravitational field (your active mass, presumably).
>> 2 The mass acting as test particle feeling the force (passive mass).
>> 3 Inertial mass determining which acceleration results from the force.
>>
>> So the acceleration that occurs depends on three kinds of mass. Or do
>> you work with other subdivisions?
>
> Well, if you consider two particles with signs of masses given by (I1,A1,P1)
> and (I2,A2,P2) respectively, then according to Newton's law of gravitation,
> the force on particle 1 due to particle 2 satisfies,
>
> F12 = I1 m1 a12 = G P1 m1 A2 m2 / r12^2
>
> So the direction of the acceleration depends upon the product I1.P1.A2.
> This means that if we change the sign of both I1 and P1 for particle 1,
> then the direction of the acceleration on it will not change. This is why,
> for example, a particle of type (-+-) interacts gravitationally just like
> ordinary matter, even though it has negative inertial and passive mass.
Only if the test particle is accelerating freely, i.e. detached from
all else! If you put it on a scale, instead of letting it move freely,
you would immediately see whether it has ordinary or negative passive
mass. (But then of course it does not accelerate because it is fixed.)
And even if it is not fixed, but you let it accelerate while attached
by a rope to an ordinary mass M, you will easily see different results.
For instance if you let the rope make a 90 degree turn around a pulley
between the masses, like in the drawing below, the mass M does not feel
the gravitational field (assumed vertical for the moment) but it does
add to the total inert mass that has to be accelerated.
________M2
/O
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(T) <-- Test mass (T) attached by rope to other mass M.
So if only gravity existed, and no other forces, you would probably
be right, but I think Newton's laws were meant to be applicable more
generally than that, and with other interactions added, you really
get 8 different behaviors for the 8 types of particles you mention.
--
Jos
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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