For some reason, when I’m deeply involved in reading something at my desk, my mind is fully occupied, but my hands can’t be idle. (The devil finds work for idle hands?) So I’ll finally emerge from what I’m reading to discover that my hands have taken the paper clip off the document, unbent it, and twisted it into a new shape.
The other day, I noticed that when I twist the metal paper clip very quickly, it becomes hot to the touch (not warm, but burning hot). Why does it do this?
Are you familiar with the concept that a metal expands when heated and contracts when cooled, the term is heat-induced strain (where strain refers to the movement of metal)? The same thing happens in reverse too, if you apply a strain (that is movement) to the metal it will heat up.
I think the quasi-scientific answer you’re looking for is that the crystal planes within the metal slide relative to eachother as you move the paperclip. The resulting friction causes heat. That’s about the best I can do without my Strength of Materials textbook.
Uh huh. What he said.
In a broad sense, it’s conservation of energy. In physics, if you exert a force on a system (such as a paper clip) over some distance, you add energy to the system in some form or another. In this case, the energy you add to the paper clip ends up as heat.