A decent "k" value for newton's law of cooling for water? Recently I've been trying to cool some water to a specific temperature from boiling. It doesn't have to be super accurate (within about 5° degrees Fahrenheit or 2° Celsius) but the only thermometer I have access to is just for ambient temperature, and I'm not about to dunk that thing in boiling water until the temperature drops ~30 degrees. So what I need is a k value I can use for water so I can be relatively close to my desired temperature. What I'm assuming is that I have a magical floating cube of water where the only insulation is from the water its self. I'd also like to be able to make the constant based on various volumes of water so if that could be kept as a variable, V, that would make it much easier for me for when I plug this whole thing into excel. It's been quite a while since I've had anything I could consider a thermodynamics class so forgive me if I'm a little slow on picking up what you're putting down (don't you love the dated phraseology?). Any and all help would be greatly appreciated.