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
There’s physics that everything follows, the sparks example will still make a sound. You’d be better off asking what made each thing happen.
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.
> What dictates what percent of the energy turns into what type of energy, etc???
There are energy thresholds that are required to be met in order for things to happen. Like.. heating up oil doesn’t just cause it to combust, but if you put enough energy into it, i.e. with fire, it will. Also, the material for the reaction affects how the energy is absorbed or change. In the case of flint, it’s a matter of the hardness of the material and it being able to absorb and distribute the force applied without breaking, while also shaving off some electrons and molecules from the metal used.
This is really only scratching the surface though, no pun intended.
As another pointed out, you have to be more specific. Your examples seem to revolve around how kinetic energy is converted to other forms of energy when one object strikes another. This will depend on many things including the properties of the materials (such as density and hardness), how fast they are moving relatively to each other, etc..
One thing I will point out though is that when you create sparks, something else is happening. The reason you get sparks is because you are releasing small bits of iron in to the air and they are oxidizing. This is a chemical reaction between the iron and oxygen, not the conversion of kinetic energy to the heat and light in the sparks.
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