everyday-lifethermodynamics
In winter, our glass window serves as a separator of coldness outside and warmth inside our room. We know that the window feels cold when we touch it. Since the air temperature is different in different sides of the window, why does the window choose to be cold ?
What's the temperature of the window ? Is it closer to the temperature outside or inside ? Why ?
The copper will heat up the drink more quickly, but it will also cool your hand and lips better than the cold liquid itself. Perhaps cool hands and lips is the feeling drinkers experience and favor. You could do simple experiment - put equal amount of drink and ice into copper and ordinary glass, and find out in which one the ice melts down first.
Short answer:
The thermometer measures actual temperature (which is the same for both), while your hand measures the transfer of energy (heat), which is higher for the pot than the air.
Long answer:
Keyword: Thermal Conductivity
The difference is a material-specific parameter called thermal conductivity. If you are in contact with some material (gas, liquid, solid), heat, which is a form of energy, will flow from the medium with higher temperature to the one with low temperature. The rate at which this happens is determined by a parameter called thermal conductivity. Metals are typically good heat conductors, which is why metal appears colder than air, even though the temperature is the same.
Regarding your second question: the thermometer will show the same temperature. The only difference is the time at which thermal equilibrium is achieved, i.e. when the thermometer shows the correct temperature.
Final remark: the rate at which heat (energy) is drained from your body determines whether you perceive a material as cold or not, even if the temperature is the same.
For reference, here is a table which lists thermal conductivities for several materials:
Best Answer
Three things to consider:
To no. 1., remember that your hand is much warmer than the glass. The glass temperature is not constant though, see below.
To no. 2., consider e.g. steel and wood. At the same temperature, what feels hottest? The steel! Why? Because the thermal conductivity is much bigger in steel than in wood. So even thought there is the same temperature difference between the materials (steel or wood) and your hand, which will result in heat transfer into your hand (so your hand heats up and it feels warm), this rate of heat transfer (that is, how fast your hand is heated up) is much higher in the steel.
But what really should explain it is no. 3. You don't loose much heat from your skin to the surrounding air inside your house. Heat transfer from you-to-air is due to convection. Now if you touch the glass, then conduction of heat starts, which is much more effective, and much more heat at a much higher rate is transfered from your skin. (And loosing heat fast is equal to feeling cold, since the molecules on the edge of your skin are cooled down faster than they can be reheated by your body.)
The glass temperature
The glass does not have just one temperature. It has a temperatur distribution throughout it's depth. See this illustration:
The yellow block is a cross-section of the glass. We have inside to the left and outside to the right.
The air on the inside has a certain constant temperature $T_{\infty,1}$ (we call it constant because there is so much air; even though the window cools down the air a bit this has no sensible effect). Near the glass the air is cooled down, and you see the temperature of the air dropping to $T_{s,1}$.
The glass then has a constant decreasing temperature inside itself. This temperature varies linearly from the temperature of the inside-surface $T_{s,1}$ to the temperature of the outside-surface $T_{s,2}$.
And the cooler ouside air is then a bit warmer with temperature $T_{s,2}$ near the glass but reaches it's constant outside-temperature $T_{\infty,2}$ as you move further out.
This not-temperature-constant boundary layer of the air near the surface of the glass is very small.
From all this we can also now see that the glass feels colder, if you touch it from the outside than from the inside!
But since it is very thin the difference might not be that big. (If you try this out, remember that it is a different story for two-layer glass windows. This can be modelled similarly and there will be a big difference in temperature distribution between the inner and outer layer of glass. The gab in between is filled with air, so here we have convection again - but in still air convection is very week and the air acts as a proper thermal isolator.)