physics-coffee, wtf!?

[ripken204]

i have a physics question here...

so you have a cup og hot coffee and u want cream in it, but your not going to be drinking the coffee for a little while. if i wanted the coffee to stay the hottest, should i put the cream in now or when i wanted to drink it? explain it... they give the equation ΔQ=KΔT

my guess it to put the cream in when ur ready to drink it, b/c the ΔT will be much less, but im not sure how to explain/prove it.

[Zxian]

Nope, put the cream in now.

Reason - the cream will cool the coffee now, so the difference in temperature will be less. That means that the total heat lost over the period of time will be less.

If you want a better reasoning - look up Newton's Law of Cooling.

[ripken204]

http://www.physics247.com/physics-tutorial...w-cooling.shtml

thx, i just found this

[Mordac85]

I can't believe you found the exact question online, and with supporting data! Now, maybe you can anwser me this. Which boils faster a pot of cold water or a pot of hot water? (I'm not sure I really agree with the notion of thermal acceleration) I'll have to see if I can find some site that's done this with the data as well.

[ripken204]

lol, my teacher was proud of me

if anyone got it right in my class, then their explanation sucked, mine was perfect.

for your case mordac, im pretty sure its the pot of hot water.

[oldwolf]

Now, maybe you can anwser me this. Which boils faster a pot of cold water or a pot of hot water? (I'm not sure I really agree with the notion of thermal acceleration) I'll have to see if I can find some site that's done this with the data as well.

Hey Mordac

I found this at Scientific American, and other versions of the same thing at other places. Also with an answer to it in reverse.

http://www.sciam.com/askexpert_question.cf...EB7809EC588F2D7