Doubts regarding the Calculations energy chart

[Austrian-Man-Meat]

I would like to speak about something which I have found to be fairly confusing. And by this I mean the chart presented here. The values presented such as 8 joules being needed to fragment a cubic centimeter of rock sound quite astoundingly low to be honest. I cant even crack or dent a rock of equivelant size with punches or by stamping on them. Other examples also include 90 joules being needed to pulverise iron which even TLT had doubts with

I am overall very doubtful of the chart presented and believe that it can effect calculations to quite a significant degree, a revision may be needed to be honest.

 

[DontTalk]

The method used is were really all our values come from. Changing a value isn't that much of a problem, changing the method is a lot. (literally every attack potency on the whole wiki more or less)

You can fargment a rock. Take a hammer and hit it, it will break and all of the energy comes from you. Where your intuitive problem comes from is that the science of destruction isn't as easy as we make it seem to be.

How you hit something something matters a lot, something sharp easier destroys than something blunt. HItting with something hard is better than hitting with something soft etc.

In reality one has to consider a shit ton of things, to the point were many methods of destruction wouldn't even be comparable (for example a very sharp razor blade can in reality probably not really be compared with a punch when it comes to durability).

Nobody here is an engineer or something, or at least most people aren't. For basic things like that to get comparability and to get things calculateable we have to rely on making simplifications.


So the values are correct, just not every form of destruction can be considered equally or at once.

 

[Austrian-Man-Meat]

I don't think I was talking about a form of destruction, more like getting a more accurate value for the method we already used. Which is afaik based on hitting something with x amount of energy until it fragments/violently fragments etc. When I see that you need 8 joules of energy to fragment a cubic centimeter of rock but when you apply the same energy to it irl the rock still stays intact that is when I believe that some experimentation or research should be conducted regarding this.

Just to assure you, I am not speaking of using sharp objects etc, all just blunt force as what seems to be recomended here. Thanks for your reply, I think I understand it somewhat better.

 

[Lina_Shields]

Seeing that a metal object (hammer in this case) has the dimensions of 1cm x 1cm x 1cm, the picture above shows that in order to fragment the rock shown below (1 cubic cm), the metal object must apply at least 8 joules worth of kinetic energy in order to fragment the rock.

This is assuming the metal object has the same dimensions as the rock.

Finding the mass of the metal object, the density of steel is 8.05g/cm^3, or 0.0085kg/cm^3

The mass of a 1cm x 1cm x 1cm = 0.0085kg.

Since KE = 0.5mv^2, and KE = 8 joules

v = sqrt(8 joules / (0.5*0.0085kg)) = 43.38m/s

This means that for the rock shown below to fragment, the metal object would have to be moving at about (43.38m/s) directly onto the rock in order to fragment it.

If that amount of force is directly applied onto you, you would be hurting.

Example: If you have a cannonball and a boulder the same size as each other, you would have to hurl the cannonball about 43.38m/s in order to fragment that boulder.