Friday, July 18, 2008

Answer: Ice Cube New Problem: Planet Formation

Ice Cube
You should wait first, then add the ice cube. It's fairly straightforward to be quantitative about this, but the thing to notice is that the ice cube has some latent heat of fusion. To melt the ice cube, you will have to put in a certain minimum amount of heat, no matter what (as opposed to adding cold water, where the water will take in more heat if the coffee is hotter). Because the coffee loses heat faster when it's hotter, let it cool a bit, then drop in the ice cube.

Planet Formation
An Earth-like planet forms from a cloud of cold, diffuse dust. How hot is the planet?

1 comment:

kangway said...

I have no clue.