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Re: [Phys-L] Internal Energy of Wood Taking a Bullet



On 2/2/2018 9:21 AM, Jeffrey Schnick wrote:
When you fire a bullet into a block of wood, while the bullet is embedding itself in the wood, it is clear that the internal kinetic energy of the wood is increasing. How about the internal potential energy of the wood? Is it increasing because chemical bonds are broken, increasing for other reasons, decreasing because the wood is being compacted bringing the molecules closer together where they find themselves more strongly bound, decreasing for other reasons, or staying the same?
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Shear and bending to fracture in the substrate heats it somewhat, increasing its temperature and increasing the  local  entropy. The recoil may increase its external kinetic energy as well.

Brian W