[jack1234]

I have a child in 6th grade and i need help on this question.

" In a 6th grade science classroom, student were investigating what melts an ice cube quickly or slowly.

Ice cube on a plastic plate melted the ice faster then Ice wrapped up in a cloth"

Why does that happen?

Based on my knowledge, ice wrapped in a cloth, the heat transfer slowly then the ice on plastic plate which is affected by the room temperature.

Any suggestions

[IITian]

Water vapour present in the room condenses on the fabric of the cloth and thus shielding the ice cube from the surrounding heat.

[Borek]

Water vapour present in the room condenses on the fabric of the cloth and thus shielding the ice cube from the surrounding heat.

Quite the opposite - dry cloth shields better. It is trapped air that isolates.

jack1234: you are right, it is all about the speed of heat transfer. One piece of ice is in direct contact with warm air, second is not. That's not all, but it should suffice.

[IITian]

I thought air would be trapped better if the cloth was air tight! which one do you think is more air tight a dry cloth or a wet one ? Moreover, with dry cloth air might go in and out thereby having the contribution from convection!

[Borek]

I thought air would be trapped better if the cloth was air tight! which one do you think is more air tight a dry cloth or a wet one ? Moreover, with dry cloth air might go in and out thereby having the contribution from convection!

If you go out would you prefer to be in dry clothes or wet clothes? This is a first hand experience that dry clothes are better at keeping you warm

Scuba divers in cold water use dry suits, because this way they loose heat much slower. Same reasoning.

Bottom line here is that air has much lower heat capacity per volume, thus it isolates much better. Removing air gives even better isolation - see Dewar flask.

In practice water always penetrates fabric, thus it won't isolate and make it air tight, it will make the cloth wet and less isolating. Dry suits used by scuba divers are close to your idea (isolated air tight fabric) but they don't allow direct contact of cloth with water, and for a good reason.

[IITian]

If you go out would you prefer to be in dry clothes or wet clothes? This is a first hand experience that dry clothes are better at keeping you warm

Wet clothes make us feel cold due to a different reason. They'll take up latent heat (fromn our body) and evaporate. This'll make us feel more cold. This is unlike the situations we are discussing here.

[Borek]

Wet clothes make us feel cold due to a different reason. They'll take up latent heat (fromn our body) and evaporate. This'll make us feel more cold. This is unlike the situations we are discussing here.

It is additional factor, but it doesn't change the situation. Even if there is 100% humidity (so there is no evaporation) you will loose heat much faster in the wet clothes.

When replying use "quote" button, this way it is obvious which text is yours and which is not.

[IITian]

It is additional factor, but it doesn't change the situation. Even if there is 100% humidity (so there is no evaporation) you will loose heat much faster in the wet clothes.

When replying use "quote" button, this way it is obvious which text is yours and which is not.

I agree that the thermal conductivity of air is lower than that of water (depends on a lot of things as pore architecture, humidity, temperature, etc.) but is that all?