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# decay into photons

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1. I don't know how to find the final energies of photons. I can find their momentum but not then their velocity, because their rest mass is zero.
For example,
2pc = E
2ymvc = E

but m is 0.. help

There is no wavelength given.
2. (Original post by StarvingAutist)
I don't know how to find the final energies of photons. I can find their momentum but not then their velocity, because their rest mass is zero.
For example,
2pc = E
2ymvc = E

but m is 0.. help

There is no wavelength given.
How have you found their momentum?

Remember, the de Broglie wavelength of a particle (such as a photon) is given by lamda = h/p.

The energy of a photon is then found from E = hf = hc/lamda.
3. (Original post by Ollie231213)
How have you found their momentum?

Remember, the de Broglie wavelength of a particle (such as a photon) is given by lamda = h/p.

The energy of a photon is then found from E = hf = hc/lamda.
I don't have the wavelengths though
I got the momenta from E = pc, but this is their CM frame momentum.. do I just add the CM energy? But then they have the same energy, and according to the question, they don't..

Attachment 541377541379
Attached Images

4. (Original post by StarvingAutist)
I don't have the wavelengths though
I got the momenta from E = pc, but this is their CM frame momentum.. do I just add the CM energy? But then they have the same energy, and according to the question, they don't..

Attachment 541377541379
But if you have the momenta, can't you use that to work out the wavelengths?

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