According to the relativity theory the moving object mass should be changed.

When we measure the mass at the 273 K and at the 0 K, the two measured mass may have very small difference.

Because the electron movement at 0K is very slow.

Is this right?

If so, which one is the correct mass?

Edited December 27, 201015 yr by alpha2cen

A system at rest and at a temperature T1 has more energy than at T=0, and thus it will have a greater mass. It is not correct to say that a moving object has more mass; that energy is already accounted for in [math]E^2 = m^2c^4 + p^2c^2[/math]

Thank you for good answering.

If so, the temperature for storaging the international standard mass is important, too.

Thank you for good answering.

If so, the temperature for storaging the international standard mass is important, too.

 

No, not really. You would be comparing it to another mass at the same temperature, so the difference due to temperature is zero if they are the same material. And also because we can't measure it that precisely. The metals' heat capacity is of order 100J/K for a kilogram, so the change in mass will be ~10^-15 kg per degree. Many orders of magnitude smaller than what we could measure.