How come when you hit 2 rocks together it makes sound energy but if I hit two other rocks together it can make sparks, whatever kind of energy that is. When you use a newtons cradle, the potential energy turns into: heat energy, sound energy, and maybe other stuff. What dictates what percent of the energy turns into what type of energy, etc???
In: Physics
All physical things we interact with at their core are made of atoms bonded to each other in various ways. These properties are dictated by the types of bonds that can be formed and broken, and the resulting interactions between atoms.
Sometimes atoms are very loosely bonded, so the object just breaks apart, and the pieces absorb the energy. Sometimes they are very rigidly bonded, and the energy goes into heat and sound. If the bonds are very good at transferring vibrations internally, more might go into heat. If they’re very good at interaction with atoms of gas on the surface, more might go into sound. If you had a powerful computer, you could simulate a giant system and see all of these processes take place, and see how tweaking the types and amounts of these bonds change where the energy goes, just like changing a large physical system can change where macroscopic energy goes.
Interestingly in the case of flint the energy that makes sparks actually doesn’t come from the impact. The bonds of the material are weak enough that you can shave off some iron with the blow, and this iron does not have a protective layer of oxidized iron around it. As a result it immediately reacts with the oxygen in the air, essentially catching on fire (if it seems weird for a metal to burn, look up steel wool burning!). So the energy is actually coming from the inherent potential energy between iron and oxygen, as if they were two distant planets, releasing it as they slam into each other.
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