Eavesdropper Gary Snethen <gsnethen@gmail.com> offers Date: Sat, May 28, 2016 at 12:48 AM Subject: Re: Chinese tea puzzle To: Bill Gosper <billgosper@gmail.com> My initial intuitive guess: It will cool the fastest if you allow the tea bag to reach a temperature halfway between the tea and the air and then transfer it in and out of the tea as rapidly as possible. This is because the rate of cooling of the tea (and heating of the surrounding air) is proportional to the temperature difference between the bag and the tea (or air). Therefore, the rate of heat transfer will be maximized if we keep the temperature delta as high as possible in both the heating phase and the cooling phase. With that said, transferring the tea bag in and out of the tea rapidly (at 50% duty cycle) will ultimately reach the same rate of heat transfer in stable state, but allowing the tea bag to first reach the midpoint temperature will maximize the cooling rate sooner. ---Gary On Sat, May 28, 2016 at 12:11 AM, Bill Gosper <billgosper@gmail.com> wrote:
I pour a cup. It's too hot and too weak. With chopsticks I remove the bag from the pot and dunk it repeatedly in my cup. Will my tea cool faster if I dunk up and down rapidly, or pause several seconds between immersions? --rwg