**Ask a monkey a physics question thread**

[OngBonga]

Cool thanks.

I guess the next step is to see if I want to start brewing at the recommended 96C instead of the ~99C I've been doing.

Bear in mind that the act of pouring the water from the kettle causes a temporary but large increase in surface area, and thus an increased rate of heat transfer between the hot water and the cool atmosphere. Point being, there's very little chance that the water is ~99 by the time it's in your cup.

[wufwugy]

Bear in mind that the act of pouring the water from the kettle causes a temporary but large increase in surface area, and thus an increased rate of heat transfer between the hot water and the cool atmosphere. Point being, there's very little chance that the water is ~99 by the time it's in your cup.

See, I was totally gonna ask about this, but I thought that the answer would be too dependent on things.

Is there some rule of thumb for how quickly, say, a cup of boiling water cools down once pulled off burner or during the pour?

[Savy]

See, I was totally gonna ask about this, but I thought that the answer would be too dependent on things.

Is there some rule of thumb for how quickly, say, a cup of boiling water cools down once pulled off burner or during the pour?

Boil your kettle, wait 30 seconds and it'll be ok for coffee.

Naw I'm pretty sure you're right. It was a confusion I had because in class it was presented as if the entire quantity had to be 100C for the phase change to begin. However, this doesn't pass the logic test, where you can say look at the ocean, parts boil while the rest doesn't. Maybe I misunderstood what was said in class, but in my defense my teacher was not good.

If you took 100ml of water and heat it up assuming some bits get hotter than others faster then if you look at the localised spots and say there's a spot of 10ml that is 100C then why would that 10ml not be boiling? It would in isolation.

There may fully well be a reason but makes sense to me.