Ice Cutting Experiment

All right, we're ready to do this experiment. I have the two 1.5 kg masses separated by a copper wire, and my housemate and assistant, Colette, has the two 1.5 kg weights separated by some fishing line. They're both the same thickness, so we're going to put them on simultaneously and see how they go in cutting through the ice. How's yours? [Music]

All right, we're roughly halfway through the experiment, but I ran into trouble. The copper wire actually pulled out of these weights, and so they fell to the ground. At this point, it looks like the copper was doing slightly better than the fishing wire, but I've had to rig up a new copper, and so I'm going to try it in a different spot and let this new copper compete. I also scraped off the insulation; there was some enamel coating on the copper wire, so I've scraped that off, so it should just be straight copper wire now. So let's see how it performs. [Music]

All right, it's half 1, but it looks like the experiment is over, and we have a winner. A copper wire pulled clean through the block of ice, while the fishing line is still stuck in there. So why was that? Why is the copper better able to pass through this ice block than the fishing line?

Well, I think the answer may have something to do with thermal conductivity. The copper is a better conductor of heat than the fishing line. That's important because as the wire passes through, the ice refreezes once the wire has passed, and that releases heat. If that heat is transferred quickly, it passes to the ice below, melting it and allowing the wire to move further and faster.

Now regelation is not just some abstract useless scientific concept. Every time you make a snowball, you compress those ice crystals of the snow, and when you compress it, it melts a bit, turning into water. But as you release the pressure, it refreezes. So what we've made is a snowball. Think about that next time you're having a snow fight.