whp@cbnap.UUCP (01/16/84)
There is an old physics puzzle I recently came accross again, only now I'm not so sure of the answer. It goes like this: You have just poured yourself a hot cup of coffee. As you are about to pour in some milk, the door-bell rings. To keep the coffee hottest longest, do you add the milk immediately or should you add the milk later (just before you drink)? If the milk was kept cool in the refrigerator before the door-bell rang, is the answer affected?
dnc@dartvax.UUCP (David Crespo) (02/01/84)
in a perfect insulator, such as a thermos, no matter what temp you keep it at, it won't lose any heat, so then it would seem that one would just as soon cork it up and wait, since lowering it to final temp before or after will not affect its temp wwhen final. however, no insulator is perfect, except thermos brand thermoses, which they don't have inthis part of arkansas, so: case 1 is i have milk and i have coffee, both in insulators (aha, this means above, that the milk must also be in a thermos, else it will cool while we wait, in which case we either get a lower final temp when we pour it in as we return, but longer (useless) maxheat (strictly speaking), or a higher finaltemp since we pour it in earlier, assuming milk at greater than room temp, or if milktemp init is lower htan room, it will warm, and when poured in later it will reach a higher final temp than if it were poured in before leaving, though the coffee hen is at a lower temp during departure, so we need some measure of degree-minutes, which we are trying to maximize, or a highest final appreciation temp, which is what I assume we want, unless we want to be really clever and don't care, since we are realy going for perfect temp, not maxtemp. see? this all assumes of course that we have a perfect insulator, (it doesn't matter whether we pour the milk in the coffee or vice versa, or both in a third container (unless that would take too long))so that gat least on temp remains constant. what if we let the coffee (since we have only a small insulator), then final temp falls,
dnc@dartvax.UUCP (David Crespo) (02/01/84)
more to follow....
mcewan@uiucdcs.UUCP (mcewan ) (02/07/84)
#R:dartvax:-66300:uiucdcs:24400042:000:55 uiucdcs!mcewan Feb 6 13:01:00 1984 How long has net.physics been a haven for illiterates?
richard@sequent.UUCP (02/08/84)
The only solution is to take the phone off the hook *after* you pour the coffee, but before you pour the milk in. By taking the phone off the hook, you pretend you're talking on the phone. This will invariably force the door-bell to ring. If this doesn't work, try dialing the operator. It sometimes helps to have someone on the other end. If it *still* doesn't work, try filling the bathtub, or running the shower for a few minutes. That should do it. Or you could skip the whole thing by pouring the hot coffee into cold milk. from the confused and bleeding fingertips of ...!sequent!richard