frankuitaalst

2008-Sep-09, 07:50 AM

I'm a little confused about the Energy - Mass relationship : E=mc².

E is said to be the total (internal) energy of a mass , in which are included heat , chemical energy , nuclear energy aso...

The expression is further extended to take into account the kinetic energy into the expression E²=m²c²c²+p²c² . This still is quite comphrehensible .

But how about potential energy of such a particle in a gravity potential field ?

Is potential energy in this case considered as an external source of energy , and thus covered by the field energy ?

Second question :

some mass can also have a charge such as protons , electrons , ions...etc...

I can imagine that having or not having a charge changes the "internal energy" of a particle . Is this correct ? Or is the property of having a charge is considered of only having an influence in an external field ?

Is there an analogue formula E= Q.c² ?

I think my confusion comes for a great deal from the mass-charge analogy when we consider the following equations : Ep=GMm/r and Ep=kQq/r² , giving an analogy between Mass energy and Charge energy .

As I'm typing this I realise that both energies are potential energies and therefor may be considered as "external" energies and therefor not appearing in the E=mc² formula.

But I don't know if this is correct .

E is said to be the total (internal) energy of a mass , in which are included heat , chemical energy , nuclear energy aso...

The expression is further extended to take into account the kinetic energy into the expression E²=m²c²c²+p²c² . This still is quite comphrehensible .

But how about potential energy of such a particle in a gravity potential field ?

Is potential energy in this case considered as an external source of energy , and thus covered by the field energy ?

Second question :

some mass can also have a charge such as protons , electrons , ions...etc...

I can imagine that having or not having a charge changes the "internal energy" of a particle . Is this correct ? Or is the property of having a charge is considered of only having an influence in an external field ?

Is there an analogue formula E= Q.c² ?

I think my confusion comes for a great deal from the mass-charge analogy when we consider the following equations : Ep=GMm/r and Ep=kQq/r² , giving an analogy between Mass energy and Charge energy .

As I'm typing this I realise that both energies are potential energies and therefor may be considered as "external" energies and therefor not appearing in the E=mc² formula.

But I don't know if this is correct .