/sci/ - Science & Math

[Anonymous No.5609192]

What does the speed of light have to do with mass-energy conversion in nuclear fusion/fission?

[Anonymous No.5609195]

>>5609192

c squared would be the constant?????

[Anonymous No.5609198]

>>5609195
>?????
An extreme question.

[Anonymous No.5609200]

Yes. I understand. But WHY the speed of light squared? Why that as the constant? Coincidence, I assume not.

[Anonymous No.5609206]

>>5609198

naw.. I'm just areally sloppy typist.

the matter-energy equivalency applies to any situation where mass is converted directly to energy, which happens in both types of nuclear reaction... If you want the derivation of the equation, I recommend reading Einstein's little book.

[Anonymous No.5609208]

>>5609192
since energy goes to infinity as v -> c and you expand it in terms of v you get the mc^2 as the constant term.

[None !3BananaXFw No.5609209]

>>5609200
The speed of light is just the speed limit of the universe

You could google a derivation if you'd like to

[Anonymous No.5609217]

Einstein postulates that the speed of light is the same in any reference frame. This means intuitive nontions like Galilean transformations (if I'm on a train that travels north wrt earth at 100 mph and I walk north wrt the train at 5 mph then I move north at 105 mph wrt earth) are fundamentally flawed.

You need Lorentz transformations to go from one frame to the other, which obviously depend on the speed of light (since that's what has to be constant).

It shouldn't come as a surprise that the expression for energy associated with movement also contains the speed of light (where before it was just <span class="math">E_k = 0.5mv^2[/spoiler].

To get that expression for rest mass you need to do a little more work, but it's not very difficult. If you're interested, you can find this in any undergrad special relativity text and all you really need to know is some classical physics and the concept of Taylor series expansion.

[Anonymous No.5609262]

define mass

define speed

define light

define energy

[Engineer No.5609316]

Energy released (as heat Q), <span class="math"> Q=mc^2 [/spoiler] from radioactive decay.

Energy released in nuclear fission = change of binding energy. Where binding energy of a nucleus = <span class="math">\Delta m c^2 [/spoiler]. <span class="math">\Delta m [/spoiler] is the mass defect, so you can work out the energy.

So for a particular nucleus of A nucleons and Z protons
<span class="math">\Delta m = Zm_p + (A-Z) m_n - M_{Nuc} <span class="math">[/spoiler][/spoiler]

[Nuka-Cola; Alpha Apple No.5610421]

here
http://www.youtube.com/watch?annotation_id=annotation_295893&feature=iv&index=1&list=PLED25F943F8D6081C&src_vid=Wp20Sc8qPeo&v=hW7DW9NIO9M