Why is it that as soon as you pour tea in a cup, it gets extremely hot but the handle of the cup doesnt get heated up? 
Re: The cup question
transfer of heat
Re: The cup question
The heat transfer between hot fluid and cup surface occurs thru the cup wall thickness. Thicker the cup wall slower the heat transfer rate.
Transfer to cup handle occurs along length along the handle. So portions of handle close to cup handle intersection hotter than portions away. The area of x section thru which heat flows is simply cross section area of handle. Which is quite small. So heat transfer rate much smaller.
As philosophyyyy stated in a laconic manner.
The cup question
That's so high school. We used to have questions about conduction, convection and radiation lol
Re: The cup question
True that. But we tend to forget high school stuff. Always good to review.
Plus this was a cool question. Not straight out of a book.
Re: The cup question
Thanks guys , sometimes its awesome to be reminded of things that have settled the dust in the subconscious 
Re: The cup question
We didn't consider radiation. Temp not high enough. So negligible?
Convection - if vessel aspect ratio is 2/1 ht/dia, it can be assumed heat loss from top surface won't impact bulk temperature in liquid.
There is convective loss from walls and bottom. Since temp at wall >> handle convective losses from wall will be higher than that from handle. Depending on ambient temperature and also air flow, the convective loss rate would vary. All this means is as time increases the wall temp and handle temp converge.
If aspect ratio is say 1/2 (wide cup), this will lower bulk temp faster. So wall temp is now lower. Delta T wrt handle lower. This in turn lowers heat loss rate from wall. So wall temp decreases at lower rate. Probably time taken to converge with handle temp may be same!
Just some thoughts that occurred. Need not be correct.
The cup question
Oh is that "cup" question
Re: The cup question
Oh is that "cup" question
lol...i wondered too! :D
Re: The cup question
What does "a slip between the cup and a lip" really mean? What does it have to do with this heat transfer problem?
The cup question
This whole thread reminds me of cup song
Re: The cup question
We are all ears.
Re: The cup question
We are all ears.
No ... lips
Re: The cup question
Check that. We r all ears and lips.
Re: The cup question
Agree with what Southie said ....
The surface area of the cup is in direct contact with the hot fluid and the heat loss from the fluid to the area around the cup is high because the surface area contact is high. The handle on the other hand (mind the pun) is connected to the cup which in turn is touching the hot fluid. The handle has only two small bits in contact with the cup, the only heat by conduction that can enter the handle is via those two prongs that touch the main cup section. Of course the heat will spread out to colder areas and by the time it gets to the part that you hold it has spread and the intensity of the heat has diffused.
This means that the heat felt in the handle is related to the conductivity of the material and the surface area in contact with the heat source and the amount of dissipation is allowed before coming in to contact with the fingers.
You also notice that when a cup without a handle is nearly full of hot tea the best place to hold it is at the rim where there is no tea directly adjacent to the part being held ... this is because the only heat transfer is taking place through the vertical cup thickness and any sideways heat transfer is negligible.
Re: The cup question
I like the last para re w/o handle case.
Pun minded and noted.
Re: The cup question
Primary school: Mam, agar handle bhi garm ho jaye to cup kaisay pakrain gy aur chaye kaisy pe jaye gi? :)
Re: The cup question
No ... lips
ewwwwww. im reporting this!!
Re: The cup question
that’s me. 