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Q & A: heating by bending

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Most recent answer: 12/25/2015
Q:
Heating by bending. What I think: In a solid, heat is the considered to be caused by the motion/vibration of atoms/molecules. We know that if we bend a metal rod it will get heated. Part of the energy used to bend the rod will be converted to heat. Rest probably will be converted to potential energy of the atoms/molecules as their intermolecular distances will be altered. My question: 1. How exactly, is this process of bending causing the molecules to vibrate more causing to produce heat? 2. Is there any mistake in my thinking?Thank you
- Himadri (age 60)
Orange, Ct, USA
A:

Your ideas are basically right. I would not, however, say that heat is  "caused by the motion/vibration of atoms/molecules". In typical solids, thermal energy mostly is "the motion/vibration of atoms/molecules".

Here's one way to think of how the energy flows from bending to heat. As you say, when you bend the rod atoms ae forced into positions of higher energy. There are some deformations, little cracks, extra atoms crammed into places where they don't fit well, etc. As the atoms jiggle around, they tend to fall back to low energy positions. The energy that is released rattles around as little sound waves- "the motion/vibration of atoms/molecules" or "heat". Most of this process goes on during the bending, but a little bit goes on afterwards because some of the defects are long-lasting.

Mike W.


(published on 12/25/2015)

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