QuoteThis has bugged me couple of days now.
If I had bucket of room temperature water (10 liters), would it be possible to cool an object (like a rock) so cold that it would freeze all the water in the bucket. Let's say the bucket would be 20 liters so no water would escape even if the object would displace 10 liters. So how cold the object would have to be? How big would it have to be? What material would it have to be?
I usually think about situations at the "limit" to solve this kind of problems. So let's cool a bucket of water till about (just a bit more than) 0° C. Then it's quite obvious that putting an object with an adequately lower temperature will suffice to freeze the water. Exact temp and mass of the object I don't know, but it's surely possible, under certain conditions, as long as you don't put restrictions on the mass and temperature of the object. Real life restrictions could probably involve the lower temperature easily achievable. I believe you can use liquid nitrogen to reach really low temps.
P.S. Objects actually happen to freeze water even as we speak: never noticed how the ice is usually found over car's windows, even when puddles aren't frozen?