Re: [Phys-l] Relativity Question

[Hugh Haskell <hhaskell@mindspring.com>]

At 08:18  +0800 5/8/07, <carmelo@pacific.net.sg> wrote:
> Are you suggesting that we should not assign mass change to the 
> compressed spring? Or should we also include the "human body" or the 
> object which compress the spring? Hence, we should conclude that the 
> total mass of the system (spring and the agent which compress the 
> spring) is constant?
>
> This will be more consistent, right?
That's a good question, and I'm not sure I have an answer to it. The 
forces involved in compressing a spring are not so simple as 
gravitational or electrical forces or nuclear forces that we use in 
calculating binding energies of these merging systems, or to figure 
out how much energy we have to put into them to separate the parts.

Since the electrical forces that are released when one allows the 
spring to expand are all internal, perhaps this is an example of 
something that can be thought of as a complete system in itself and 
thus has the energy stored within it, so we can think of the mass of 
the spring as increasing when it is compressed and decreasing when it 
expands.

Since I have not thought much about this example, I will await the 
opinions of others who may have given it more thought than I have.

Hugh
--

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Hugh Haskell
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<mailto:hhaskell@mindspring.com>

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