Is the Law of Conservation of Mass correct or incorrect? (Read Description)

Posted by: Dishoungh

I think that it is wrong because how can an object retain its original mass quantity when it has changed significantly. For instance, when a woman/man loses weight, they must lose their mass. The gravitational acceleration is still the same right? So, I don't understand the logic of "mass can't be created or destroyed." I mean, you're eating a sandwich, so aren't you eating mass? Maybe, the definition means something else. If it does, let me know in the comments because this law doesn't make sense. It makes

  • Correct

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83% 5 votes
17% 1 votes
  • For the Women losing weight, she is losing it from working out, trading the energy from Chemical to Mechanical Energy. With eating, you are displacing Mass, same with everything really.

  • Yes, according to the law of conservation of mass, actual physical matter is not being destroyed when someone loses weight. The mass is instead transferred out of the body (or used for certain purposes. It's impossible to destroy mass or create it, so destruction of a sandwich through mechanical means is merely breaking down the sandwich into a different form, which is to say a bolus. The law of conservation of mass is the reason most scientists are in favor of the big bang theory, which states that all the mass in the universe was gathered in one spot (known as a singularity), rather than coming out of nothing.

  • In terms of what you are talking about, we can say mass is conserved. ( in scientific terms it´s more accurate to say mass-energy is conserved) What it means is that mass cannot be created or destroyed, which is true even in the examples you listed. When you lose fat, the mass is just transferred, when you eat a sandwich, the mass of the sandwich is transferred to your body. The atoms and molecules don´t "disappear". However, I don´t quite understand what you mean by gravitational acceleration changing with mass. Gravitational acceleration (small g) is a property of the gravitational field (Earth´s) , not the object.

    Posted by: Aithel
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Dishoungh says2014-05-07T23:55:54.4918128-05:00
"I mean, you're eating a sandwich, so aren't you eating mass?" Oops, I meant to say "aren't you eating matter"? That's supposed to mean that since, you're eating matter, doesn't that mean that you're consuming (destroying) mass?
livelongandprosper says2014-05-09T20:32:31.9283850-05:00
@Dishoungh - no, it doesn't. You're simply decomposing the sandwich into its constituent molecules. All the matter that made up your sandwich is still there in your stomach - it's simply changed form. Some of it will be assimilated into your own matter and some of it will be expelled. The point is, the atoms that made up your sandwich still exist.
Dishoungh says2014-05-09T20:57:24.5851081-05:00
@Oh, I think I get it. So, when you eat the sandwich, that mass transfers to you. Is that how you "gain weight?"

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