Does an A mass always give the same amount of energy?

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Discussion Overview

The discussion revolves around the relationship between mass and energy, particularly in the context of a 5kg mass and its behavior when traveling at relativistic speeds or when interacting with anti-matter. Participants explore concepts from relativity, energy conversion, and the nature of mass.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether a 5kg mass traveling at the speed of light would yield the same energy output when mixed with anti-matter, suggesting a misunderstanding of relativistic physics.
  • Another participant clarifies that a mass has energy in the form of its rest mass and that annihilation with anti-matter would release energy as photons, but emphasizes that massive bodies cannot reach the speed of light.
  • There is a discussion about the distinction between rest mass and "net mass," with some participants explaining that net mass increases when an object is in motion relative to an observer.
  • Concerns are raised about whether mixing matter with anti-matter results solely in electromagnetic energy, with some participants noting that this energy can reform into mass and that annihilation is not always guaranteed.
  • One participant highlights that E=mc² applies to mass converting to energy, while kinetic energy considerations at relativistic speeds complicate the energy calculations.
  • Questions arise about the implications of forces on mass and the nature of energy produced from electromagnetic interactions.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the concepts of mass and energy, with some agreement on the principles of energy release during annihilation, but no consensus on the implications of relativistic speeds or the nature of mass in different frames of reference.

Contextual Notes

Participants exhibit uncertainty regarding the definitions of rest mass and net mass, as well as the conditions under which matter and anti-matter annihilate. There are unresolved questions about the nature of energy produced from electromagnetic interactions.

Who May Find This Useful

This discussion may be useful for individuals interested in the fundamentals of physics, particularly those exploring concepts of mass-energy equivalence, relativistic physics, and particle interactions.

Mad1kas
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hello people,


i am new at physics and i have a question that you will be able to answer !

well,
supposedly we have a subject with 5kg mass...
if we make it travel at the speed of light we will get E = 5 x 300.000 x 300.000 = 450.000.000.000 J is this the same amount of energy it will give off if we mix it with anti-matter?



P.S (soory for the noobie question i just would like to learn more and more ! )
 
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Learning is always good; great question.

A 5kg mass has (E=mc^2) energy in the form of its rest mass. If it were to perfectly annihilate into energy (from anti-matter presumably) then all of this energy would be released (as photons).

You can't accelerate any massive body TO the speed of light - you can only get them close to the speed of light. If you do that however, you drastically increase the energy of the body to significantly more than the rest mass. At relativistic speeds, E=mc^2 isn't the total energy, just the rest mass energy.
If you add the gamma (lorentz) factor, E='gamma'*mc^s -> that represents the energy stored in the net mass (the relativistic mass); but still does not include the kinetic energy.
 
lzkelley said:
A 5kg mass has (E=mc^2) energy in the form of its rest mass. If it were to perfectly annihilate into energy (from anti-matter presumably) then all of this energy would be released (as photons).


Does this mean that mixing matter with anti-matter can only give off electromagnetic energy?

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When we say "at rest" (invariant mass) we mean when the aren't any forces on the mass?(i read it on wiki and understood nothing)

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What's net mass??
 
rest mass, is the mass in a reference frame in which the object is stationary. if you see an object moving past you, it has a mass (which i was calling "net mass") that is larger than its rest mass. Does that make sense?
(If you put forces on the object - then it makes it even more complex - but don't worry about that).

If you mix matter with anti-matter, if they collide / annihilate, they will give off only and purely E&M energy. Two things are noteworthy:
first, often the E&M energy will reform into mass; second, matter and anti-matter don't always annihilate.
 
Mad1kas said:
hello people,


i am new at physics and i have a question that you will be able to answer !

well,
supposedly we have a subject with 5kg mass...
if we make it travel at the speed of light we will get E = 5 x 300.000 x 300.000 = 450.000.000.000 J is this the same amount of energy it will give off if we mix it with anti-matter?



P.S (soory for the noobie question i just would like to learn more and more ! )

I think you are thinking any object posesses mass moving at speed of light will have E=mc^2. E=mc^2 have nothing to do with object moving at the speed of light. It just saying if one convert pure mass into pure energy, that's what you should get. I think if an object with near c speed will still have conventional kinetic energy 1/2mc^2. Particle accerlator graph show that energy spike up to ifinity near speed of light. Of course that is due to scientists keep adding energy to the particle.
 
Last edited:
lzkelley said:
rest mass, is the mass in a reference frame in which the object is stationary. if you see an object moving past you, it has a mass (which i was calling "net mass") that is larger than its rest mass. Does that make sense?
(If you put forces on the object - then it makes it even more complex - but don't worry about that).

If you mix matter with anti-matter, if they collide / annihilate, they will give off only and purely E&M energy. Two things are noteworthy:
first, often the E&M energy will reform into mass; second, matter and anti-matter don't always annihilate.

so the mass of an object is different when moving and different when its stationary??


and what kind of mass will E&M energy create??


thanx for you assisstance friend
 

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