MMC
24th August 2006 - 11:11 PM
Hi mick,
You must forgive my loose usage of terminology when discussing this earlier. I'm usually in a hurry and tend to leave the semantics to everyone else.
QUOTE
If I have two of the exact same sealed containers containing the exact same
number of molecules of the same substance, sitting on two very precise weighing
scales located at the same position equdistant from the earths centre their mass
will be the same.
How can I make one container weigh more than the other without moving either of
the containers ?
If I were to heat the container thereby exciting the molecules would this alter
the mass registering on the scale.
Mass and weight are not the same things. Mass is static, whereas weight is can alter with speed. Regardless of where anything is, or what velocity it is travelling at, its mass will always remain the same.
QUOTE (->
| QUOTE |
If I have two of the exact same sealed containers containing the exact same
number of molecules of the same substance, sitting on two very precise weighing
scales located at the same position equdistant from the earths centre their mass
will be the same.
How can I make one container weigh more than the other without moving either of
the containers ?
If I were to heat the container thereby exciting the molecules would this alter
the mass registering on the scale.
|
Mass and weight are not the same things. Mass is static, whereas weight is can alter with speed. Regardless of where anything is, or what velocity it is travelling at, its mass will always remain the same.
Mass and Weight
The mass of an object is a fundamental property of the object; a numerical measure of its inertia; a fundamental measure of the amount of matter in the object. Definitions of mass often seem circular because it is such a fundamental quantity that it is hard to define in terms of something else. All mechanical quantities can be defined in terms of mass, length, and time. The usual symbol for mass is m and its SI unit is the kilogram. While the mass is normally considered to be an unchanging property of an object, at speeds approaching the speed of light one must consider the increase in the relativistic mass.
The weight of an object is the force of gravity on the object and may be defined as the mass times the acceleration of gravity, w = mg. Since the weight is a force, its SI unit is the newton. Density is mass/volume.
http://230nsc1.phy-astr.gsu.edu/hbase/mass.htmlThe scientific community is pretty much agreed that gravity is a quantizied field, comparable to the electromagnetic field, in that, it propagates in waves. Knowing this, it is safe to assume that it suffers from constructive and destructive interference.
This is the key to altering mass...and faster than light travel...
bbester
25th August 2006 - 11:51 AM
But if you could accelerate the molecules in the container relative to the earth, or cause their positions relative to the earth to be different their weight would be different. If you could accelerate to near light speeds you could measurably see a difference in mass as well. I think a big problem with these types of thoughts it is assumes a homogeneity in the universe that simply does not exist. It would be more difficult to have the type of exact requirements possible that would ensure equal weight than different weight. Calculus is cool, but we have to make some huge approximations about equal distributions, etc. for the formulas to be easy enough to get a nice simple answer.
Additionally if you heat the container to the point of creating a fusion reaction inside then you can definitely alter the mass by converting some of it to energy and allowing it to escape....
Another way to thinking of it is put the 2 situations on either side of an equals sign, in the real world you probably never can, in a though experiment if you start there then you end up there unless you make operations to only one side of the equation. So are you interested in pushing the limits of the math or the physical universe?
Ulimately all of our equations and sciences ultimately serve the purpose of explaining or predicting observation, not what really is.
mickletterfrack
25th August 2006 - 01:51 PM
I posted this on another thread and I got this reply ... by heating the container and injecting Energy into it does this mean the Mass is altered also , thereby the weighing scale under one of the containers will detect a change in the weight.
Granted its a theoretical experiment .
Posted by Why Not ...
E=mc^2
We start with containers A and B and say that each container has a mass of 1kg.
We then pump 3,600,000 Joules of energy into container A (about one kilowatt-hour).
According to mass-energy equivalence (E=mc^2)...
m = E/c^2
c = 299,792,458 m/s
c^2 = 89,875,534,062,475,225 m^2/s^2
E =3,600,000 Joules = 3,600,000 kg m^2/s^2
So...
m = 3,600,000 kg m^2/s^2 / 89,875,534,062,475,225 m^2/s^2
m = 4.0055394e-11 kg or
m = .000000000040055394... kg
The mass of a small grain of sand is ~ .000000003 kg
I am trying to remember what I am currently paying per kilowatt-hour at home... and each one only equates to mass of ~ .003 grains of sand. Bummer.
It's late, so if someone sees that I messed up the calculations, please speak up.
MMC
25th August 2006 - 05:04 PM
Mick, you used 299792485, instead of 299792458 to calculate C^2.
M = E/C^2
E =3,600,000 Joules
c = 299,792,458 m/s
C^2 = 89,875,517,873,681,764
M = 4.0055402017930263558267238734528e-11
MMC
25th August 2006 - 09:11 PM
QUOTE
Thanks MMC ...
so to get back to the original question does that mean that the Mass of the
containers as measuered on the scales will have changed due to the injection of
Energy into the container ? The container thats been heated will weigh more...
Im feeling a bit like Pluto here, can someone give me a definite answer...
This should explain it...
QUOTE (->
| QUOTE |
Thanks MMC ...
so to get back to the original question does that mean that the Mass of the
containers as measuered on the scales will have changed due to the injection of
Energy into the container ? The container thats been heated will weigh more...
Im feeling a bit like Pluto here, can someone give me a definite answer...
|
This should explain it...
In the earlier years of relativity, relativistic mass was sometimes taken to be the "correct" notion of mass, and the invariant mass was referred to as the rest mass. However, Einstein himself always meant invariant mass when he wrote "m" in his equations, and never used a single "m" symbol for any other kind of mass. Einstein first deduced in 1905 that the mass (inertia) of bodies increases with their internal energy (energy content), but this mass too, is a kind of invariant mass (see section below on mass in systems).
Gradually, with the development of Minkowski four-vector notation and general relativity, it was concluded that the invariant mass was the more fundamental quantity in the theory of relativity.
Scales and balances always operate in the rest frame of objects being measured. Because in this special frame invariant mass and relativistic mass are equal, scales and balances measure both types of mass.
The common present usage in the scientific community today (at least in the context of particle physics) considers the invariant mass to be the only "mass", while the concept of energy has replaced the relativistic mass. This usage may be confusing because many kinds of "immaterial" energy (such as light and heat) may present themselves as invariant mass in objects or systems (when they are observed from the rest frame or center-of-momentum frame), and thus some invariant mass in objects and systems is subject to variation (when it is allowed to enter or escape the system as heat or radiation), just as Einstein first pointed out in 1905.
In popular science, however, the observer-dependent kind of relativistic mass is usually still presented, as it allows certain equations from nonrelativistic mechanics to retain their form (see below). Also, Einstein's famous equation E=mc^2 remains generally true for all observers only if the 'm' in the equation is considered to be relativistic mass. The modifications to this formula needed for general use with invariant mass are discussed later in "The relativistic energy-momentum equation".
As noted above, relativistic mass and invariant mass are equal in some reference frames. These frames includes the rest frame of compound objects (such as a solid composed of many particles), and also the center-of-mass inertial frame for systems of particles or objects, whether bound (such as a container of gas) or unbound (such as a system of interacting particles at high speed). The invariant mass of such composite systems includes the relativistic mass of the components. Reactions in this special inertial frame therefore do not produce changes in either mass or energy by any definition of these terms (so long as the system remains closed).
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