i_drank_what? said:So it sounds like you can break a piece of wood, in which case the sum of the mass of the two parts will exceed the mass of the original piece, or burn it in which case the mass of the sum of the parts will be less than the original whole, but there is no way to destroy the piece of wood (or anything) without either converting some mass to energy or vice versa.
Is this correct?
Thanks again everyone, I know philosophy and physics don't exactly go hand-in-hand, and it was difficult to phrase the question without explaining the theory in whole (which I promise you would have bored you to tears) but I appreciate how helpful and enthusiastic this community has been...really...you people are repairing the internet's reputation post-by-post.
Drakkith said:The current way I've seen nuclear fission and fusion described is that the reactions liberate energy and the resulting particles have less mass than the originals.
However, I have recently heard that mass itself doesn't go away or change. (Rest mass)
So unfortunently I actually don't know.
gendou2 said:If you bend plastic back and forth until it breaks, you heat it up. You might consider this added energy added gravitational mass, but you aren't increasing the rest mass at all...
Curl said:Well you are adding energy, but it is so small that touching the object will add/remove mass by a few orders of magnitude more than what you changed by breaking the object , so this isn't really a good question.
i_drank_what? said:First of all, thank you all for your timely and helpful responses,
Perhaps a better question might be "is it theoretically possible that all of the mass be preserved in the process of breaking the wood, while in the same sense impossible for the products of splitting an atom to have the same cumulative mass as the original atom," I guess I am asking if this is a fundamental difference between atoms and other objects.
I want to make an argument along the lines of "you can destroy a boat without destroying any mass, but you cannot destroy an atom without destroying any mass"
i_drank_what? said:So it sounds like you can break a piece of wood, in which case the sum of the mass of the two parts will exceed the mass of the original piece, or burn it in which case the mass of the sum of the parts will be less than the original whole, but there is no way to destroy the piece of wood (or anything) without either converting some mass to energy or vice versa.
Is this correct?.
Lsos said:Wouldn't the mass be slightly LOWER after breaking the chemical bonds, since you liberated energy stored in them?
renzagliarobb said:Not with fussion. Here energy is lost as the atoms fuse together but the combined mass from fusion is actually larger. the atoms don't have as much combined weight, but the atoms fuse and have more mass, don't they? I believe this is why the popular way to convert nuclear power in usefull energy (like at a NPP) is through fission. Fission involve taking something and making it smaller by taking the energy out of the mass. Where do you ever hear of converting nuclear power using fusion?
Originally Posted by Lsos View Post
Wouldn't the mass be slightly LOWER after breaking the chemical bonds, since you liberated energy stored in them?
Yes.
Drakkith said:Incorrect. When you fuse 2 light nuclei together, their combined mass is LESS than their individual masses were before they were combined. On the opposite end, when you split a heavy nucleus the mass of its products are less than the original nucleus. In both cases you have liberated energy. This removal of energy means that the mass has decreased.
The mass would only be lower if breaking the bonds released more energy than it took to break them in the first place. Think of a fire. In a fire oxygen from the atmosphere reacts with carbon in the fuel and forms CO2. In the process it gives off energy in the form of heat and light. In this case the mass of the CO2 is LESS than the mass of the individual Oxygen and Carbon atoms before they combusted.
Now look at water. Water is composed of 2 hydrogen atoms bound to 1 Oxygen atom. H2O. By electrolysis we can split the hydrogen from the oxygen. But guess what. This TAKES energy to accomplish and releases NONE. Now the oxygen and hydrogen atoms have a combines mass that is MORE than the water molecule that they came from.
If you remove energy from something the mass will decrease, and when you add energy it will increase.
renzagliarobb said:The combined mass! What grade are you in?
An object can't have less weight but more mass.The density can change it might be larger in size but that is not the same as something having more mass.renzagliarobb said:Not with fussion. Here energy is lost as the atoms fuse together but the combined mass from fusion is actually larger. the atoms don't have as much combined weight, but the atoms fuse and have more mass, don't they? I believe this is why the popular way to convert nuclear power in usefull energy (like at a NPP) is through fission. Fission involve taking something and making it smaller by taking the energy out of the mass. Where do you ever hear of converting nuclear power using fusion?
MayMonth said:Please forgive me for being so ignorant but I hope you guys would be willing to answer this (stupid) question of mine. Breaking of chemical bonds was mentioned here, but is any chemical bond broken when you break a piece of wood? It's still 'wood' before and after, not like it has been changed to some other compound or element. So I still don't quite understand how the final mass will exceed the initial. Please enlighten me on this.
Thanks!
ASD16 said:if u are considering each and every molecule of the wood then yes...the mass will be same...wherther it is in air or wherever...the mass will remain constant...its only in chemical reactions that mass discrepancy come up becoz of mass converting into energy and vice versa...but in any physical change like breaking into pieces etc...the mass will remain unchanged...