If I use a iron rod to hit a 3" × 12" iron plate there is the distinct sound of a metallic ring.
What is the cause of this distinct sound? Is it the crystal structure of iron or that iron is a metal and most metallic objects will ring when struck?
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2$\begingroup$ This is a physics question, and has to do with mechanical properties of materials. Also, it is not necessarily associated with metals; for example, lead certainly will not ring, while glass probably will. $\endgroup$– Ivan NeretinApr 27, 2016 at 10:12
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$\begingroup$ see this:-physics.stackexchange.com/questions/121879/… $\endgroup$– Nilay GhoshApr 27, 2016 at 11:41
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1 Answer
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Whether something rings when struck depends on the mechanical properties of the bulk material. Ringing depends on the ability of the bulk material to recover from a mechanical impact elastically with little loss of energy. That way the block of material can vibrate for a significant period of time and we hear this because of the interaction of these vibrations with air, creating sound.
The bulk properties of a material depend on both the nature of the material and the crystal structure of the bulk solid. Ringing doesn't happen if the material has ways of dissipating mechanical energy quickly rather than by vibrating elastically. This can be because of a low elasticity but also because the crystal boundaries may create ways to dissipate energy.
So some metals don't ring. Lead makes very bad bells (as does mercury when solid as demonstrated in this amusing video). Many polymers don't ring as they have many internal ways to dissipate vibrational energy quickly. But many elastic materials like brass, iron or glass do ring because they don't have any easy internal ways to absorb vibrational energy.
answered Apr 27, 2016 at 11:25
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$\begingroup$ Internal ways of absorption as in co2 or h20 within its structure? Basically gaps of air? $\endgroup$ Apr 27, 2016 at 11:52
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1$\begingroup$ @user5434678 There are lots of ways for structures to dissipate energy internally. Polymer chains in plastics can reorganise; crystal boundaries can slip or deform; air gaps can reduce material stiffness... And many materials are just not stiff enough so they deform rather than vibrating. $\endgroup$ Apr 27, 2016 at 13:45
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$\begingroup$ So no other particles in nature can form exactly in the crystal structure of iron or brass? $\endgroup$ Apr 27, 2016 at 15:16
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$\begingroup$ @user5434678 I wouldn't say that. Plenty of substances have the right mechanical properties but we know about the ones that are cheap and easy to make. BTW the shape of the object matters and the ease of making the shape from the substance will, therefore, matter. It is easy to cast bronze, for example. $\endgroup$ Apr 27, 2016 at 15:23
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$\begingroup$ How about ringing rocks? They are uncommon and rare. They ring like metal, what are the mechanics behind these stones? $\endgroup$ May 17, 2016 at 17:29