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Q & A: cold metal

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Most recent answer: 09/17/2018
Q:
Why is metal always colder than wood even if at room temperature?
- scott (age 13)
pontiex high school, canada
A:
I think what you mean is that metal FEELS colder than wood if they're both at room temperature. That's because metal conducts heat much better than wood does. Since your hand is hotter than room temperature, both the metal and the wood conduct heat away from it. Since the metal conducts better, that cools your hand faster, and that's what you feel.

Mike W.

By the same token, if the metal and the wood are hotter than your hand, the metal will feel hotter than the wood.

Tom.

(published on 10/22/2007)

Follow-Up #1: feeling heat of metal

Q:
While metals in the sun on a hot day will feel hotter than wood of identical color are they also actually hotter? I never see this addressed.
- john zimmerman (age 64)
willows ca usa
A:

It's the same reason as the cold metal feels colder. Metal conducts heat better than wood. So even when the metal and wood are at the same tmperature, you feel the temperature of the metal more.

Mike W.


(published on 05/25/2017)

Follow-Up #2: water condensing on metal

Q:
Water vapour seems to have the same feel problem - water condenses on metal sheet despite being theoretically at the same temperature as the air around it. Thoughts?
- Scott (age 60)
Australia
A:

Nice question!

I think you're asking why the water condenses on the metal rather than just condensing as droplets in the air, if they're both the same temperature. Partly, it's because it's hard for those droplets to get started without someting special for them to form on- dust, metal, etc. That's because if a few water molecules get together the energy they lose doesn't compensate for the entropy they lose. A drop only starts to grow after it reaches a critical size, and unless the vapor pressure is way above saturation that happens rarely. It also helps that the metal can quickly conduct away the latent heat that gets released when molecules start to condense together, kepping the drop from heating up. So that is related to our feelings- both depend on thermal conductivity.

Mike W.


(published on 09/17/2018)

Follow-up on this answer.