Why do frozen objects weigh more than unfrozen ones?

[jamesd2008]

Hi just out of interest. I accidentally froze 2 cans of lager. When I remembered they were in the fridge I got them out, they felt heavier, so I decided to weigh them. I compared this to two unfrozen cans of the same brand. The frozen was heavier. I know that the mass can't of changed? So how can two frozen larger cans weigh more than two room temperature ones? I assume the can is aluminum.

 

[map19]

They can't. The only possibility is the addition of frost stuck to the outside of the cans.
The hotter an object is the more it should weigh. The difference is tiny. The reason is that weight relates not just to mass but to the total energy of the object. That is the mass-equivalent energy plus the heat energy plus any rotational energy plus any other energy. The mass is many orders of magnitude greater than the others.

 

[jamesd2008]

thanks map19 for your input.