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Problem 27 Medium Difficulty

Each of the following reactions is forbidden. Determine a conservation law that is violated for each reaction.
(a) $\quad \mathrm{p}+\overline{\mathrm{p}} \rightarrow \mu^{+}+\mathrm{e}^{-}$
(b) $\quad \pi^{-}+\mathrm{p} \rightarrow \mathrm{p}+\pi^{+}$
(c) $\quad \mathrm{p}+\mathrm{p} \rightarrow \mathrm{p}+\pi^{+}$
(d) $p+p \rightarrow p+p+n$
(e) $\quad \gamma+p \rightarrow n+\pi^{0}$

Answer

(a) The reaction
$p + \overline{p} \rightarrow \mu^{+}+e^{-}$
violates
(i) the law of conservation of electron lepton number
(ii) the law of conservation of muon lepton number
(b) $\pi^{-}+\mathrm{p} \rightarrow \mathrm{p}+\pi^{+}$
This reaction violates
(i) the law of conservation of charge
(c) $\mathrm{p}+\mathrm{p} \rightarrow \mathrm{p}+\pi^{+}$
This reaction violates
(i) the law of conservation of baryon number
(d) $p+p \rightarrow p+p+n$
This reaction violates
(i) the law of conservation of baryon number
(e) $\gamma+\mathrm{p} \rightarrow \mathrm{n}+\pi^{0}$
This reaction violates
(i) law of conservation of charge

Discussion

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Top Physics 103 Educators
Elyse G.

Cornell University

Christina K.

Rutgers, The State University of New Jersey

Andy C.

University of Michigan - Ann Arbor

LB
Liev B.

Numerade Educator

Video Transcript

first question We want to look at this. Five different reactions. If you go, what is wrong with them that cost them to be forbidden? So starting at the top. Bill qwerty First reaction. Now the one thing that you pick up a steady me one it's alone. Right? So the immune number me one leapt on number IHS not probably not conserved, right Safety 11 So I asked Norm you once same 50 electron. And so the electron laptop numbers. So they're not conserve since there's only one electron and the 11 side has no electrons. So this to left on numbers are not conserved the for the Knicks, right? So to Sonny's Thanh number for the next creation we see that because the proton has a charge of plus one, The Left Insight has a total church off zero Bonnie right? The told her trustees plus two right, So church is not conserved for the next parts. We actually look at the burial number, right? So the charges at a concert Frank both is plus two but the barrel number over here the proton has burnable plus one last one So total plus two But by my pipers is a he's on, which has no barrel number. So it's zero and therefore leave fast before me plus one barrel number on the right hand side. And so bear a number is not conserved. We can actually see the same thing for the fourth equation. Neutron is also a very on so a bear a number off plus tree on the right hand side. But on the left inside is when you plus two, right, so bear a number is not conserved. Plus roughly we look at the last creation. Seaver. Obviously that 1 11 site we have e plus one church. Bonnie right, both pagosa neutral. The zero church Saudi Church is not conserved.

National University of Singapore
Top Physics 103 Educators
Elyse G.

Cornell University

Christina K.

Rutgers, The State University of New Jersey

Andy C.

University of Michigan - Ann Arbor

LB
Liev B.

Numerade Educator