What You Did
You made a cut in an ice cube, and you may have cleaved it in half!
When you let the fishing line lay on the ice, the pressure alone doesn’t do much.When you moved the fishing line back and forth while adding pressure, it didn’t take much effort to cut into the ice.
My first run of this experiment didn’t work at all! I first tried a small amount of pressure on the ice, but the line kept sliding off. The second time, I tried heavier pressure, but the ice was melting faster than the line was making any mark; I could hardly see it! So then I tried “sawing” with the hammers, and voilá! I got it to work!You can use large metal kitchen utensils if you don’t have heavy hand tools.
Try different kinds of strings in place of the fishing line