Re: [Phys-l] Conservation of energy in nuclear reactions

[Spinozalens@aol.com]

In a message dated 5/1/2009 11:56:01 AM Eastern Daylight Time, jsd@av8n.com 
 writes:

On  05/01/2009 08:20 AM, Robert Cohen wrote:
> I periodically encounter a  source that states that energy is conserved
> except during nuclear  reactions. 

Yecchhhhh.

> It is my understanding that energy  is always conserved, even in nuclear
> reactions.  

Yes.

>  The mass-energy equivalence is really between  the
> "potential" energy and the mass, so it is the *kinetic* energy  that is
> not conserved during nuclear reactions, not the *total*  energy. 

I'm not sure I would have said it quite that  way.

Energy is energy (E).

Mass is mass (m)./1/

Part of  the energy is mc^2.  We call this the _rest energy_.
I suppose you  could define potential energy to be equal to the
rest energy, but not  everybody does.  Also there are issues 
with the gauge-dependence of  typical notions of potential energy.

Let's be clear:  The equation  E=mc^2 applies in the rest frame
of the particle.  This is Einstein's  original meaning of the
equation, and also the meaning that has been  conventional among
those who do relativity for a living, and has been for  several
decades that I know of.  (I am aware that from time to time  there
have been attempts to define some notion of "relativistic  mass",
but this is a Bad Idea./2/)  Mass (m) means rest mass, so it is  
redundant but harmless to call it "rest" mass.  

Bottom  line:  Energy is conserved.  Period.  There are no  known
exceptions.  Of course to make this work you need to include  all
forms of energy, including the rest energy mc^2.

1.   http://www.av8n.com/physics/mass.htm

2.   http://www.av8n.com/physics/spacetime-acceleration.htm
_______________________________________________



))))))))))))))))))))))))))))))))))))))))
 
 
Of course the general equation is
 
             E=gamma*m*c^2 
 
Where gamma is the Lorentz factor 
 
    gamma= 1/sqrt[-b^2] 
 
 
BTW over 98% of the "mass" of the stuff that makes up that part of  the 
Universe we can see is really color force potential energy, what  Wheeler 
called "mass without mass." Next time you stand on the scale to measure  the 
force generated by your mass and the mass of the earth, etc., keep that in  
mind. 
 
 
Bob Zannelli 
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