# Hot fork

1. May 24, 2005

### ergonomics

There is something that has been puzzling me for a while, For its irrational reason.

Would a hot fork weigh more than it would cold?
I know that when particles move fast they accumlate mass.
But there is something that i am not sure about,
if they can add to the forks net mass

2. May 24, 2005

### quasar987

Though I have never seen this written in a relativity textbook, I have concluded some time ago that yes, a hot object weights more than its cold counterpart.

3. May 24, 2005

### quasar987

The mass of a body is a measure of its energy, and the energy of a body is the sum of the energy of its consituants. So we have (with "f" standing for "fork"):

$$E_{f} = m_f c^2$$

and

[tex]E_f = \sum_i^n E_i = \sum_i^n (m_ic^2+K_i)[/itex]

where we see that as the kinetic energy K_i of each particle making up the body increases, its energy increases, and hence its observed mass.

4. May 25, 2005

### ergonomics

Thank my you friend

I could prove it mathematically as well but it really puzzled me if the movement of the subatomic particles would add to the net mass

If you are supporting this claim as well then i guess i got another witness

5. May 25, 2005

### Mk

Of course the extra weight is negligable in your everyday usage. Correct me if I'm wrong.

6. May 25, 2005

### ergonomics

You are right we are talking about speeds which barely approach any noticeable speed

But still is a very interesting thing that weight is gained by subatomic movements as well

7. May 25, 2005

### Meir Achuz

Yes it weighs more. The kinetic energy of the nucleons in a nucleus contributes a measureable amount to its mass.