QED: If I make myself a nice hot cup of coffee, inevitably get called to something ‘more important’ and I’m away for an extended period of time, my cup of coffee is no longer hot. I would expect that, as part of the universes ongoing quest for equilibrium, my coffee would be room temperature, but actually it always _feels_ somewhat colder.
Is this a trick of the mind or is it actually colder somehow?
In: Physics
You can’t actually ‘feel’ temperature. What you feel is heat flux – the rate at which heat transfers.
While temperature is a component in heat flux, material composition is generally more important. Materials like water have significantly greater heat capacity and conductivity than air, so they ‘feel’ either hotter or colder than they really are (depending on the relative temperature between you and the outside medium).
If you take a thermometer and stick it into the cup of coffee that’s been cooling on your counter all day, you’ll see it’s the same temperature as the ambient air.
It is room temperature, more or less. But the inside of your mouth is much hotter than room temperature. When we feel temperature, what we’re really feeling is *relative* temperature; if you’re losing heat to something (because it’s colder than you), it will feel cold.
Your skin doesn’t experience room temperature as being quite as cold, because your skin is much cooler than the inside of your mouth, and still air does not transfer heat as well as water does.
1. You expect it to be hotter than it really is, so the perception is that it’s colder than you expected.
2. Your body heat is hotter than room temperature. It feels cold-ish to you because, to you, it is.
Part of your sense of how hot or cold something is, is how fast heat transfers from you to the object, or vice versa.
If you go outside on a winter’s day, and you see a piece of sheet metal and a tree branch lying next to one another, you know they’re both pretty much ambient temperature. But you also know the metal is going to feel way colder. Why? Because the metal is much more efficient at conducting heat away from your hand.
Similarly, if your oven has been sitting at 400 degrees for a while, both the air and the metal grating inside are around 400 degrees, but the metal is going to be much less pleasant to touch, as it conducts the heat much more efficiently into your skin.
have you ever gone for a swim and the water seemed fine until your armpits got wet end suddenly you feel cold?
Your skin is comfortable in room temperature ~25C but your mouth, armpits or any cavity of your body (anywhere you can stick a thermometer in) usually is comfortable with your internal body temperature ~36C.
This is why things you touch with your hands feel neutral (since your hands are 25C and what you touch is also 25C ) but when you put it in your mouth it suddenly a 36C versus 25C difference.
**TL:DR Different body parts maintain different temperatures.**
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