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The problem then states: estimate the minimum wavelength of the gamma ray photon.

The answer to this question is: 0.25 x 10^-11 - (binding energy of oxygen - the binding energy of F which is 0.04 x 10^-11). Then you use the hc/E = wavelength which I understand.

What I don't understand is why you would minus the kinetic energy from the energy released during nuclear fusion? Where does the kinetic energy of the proton go; does it turn into mass of fluorine? I just don't understand; I would have added the oxygen binding energy and kinetic energy of the proton together and then subtracted that value from the binding energy of fluorine-18.

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  • $\begingroup$ it is important to remember keeping the signs for the simple calculation you state, the kinetic energy of the proton is positive . $\endgroup$ – anna v Sep 20 '20 at 3:40
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Binding energy of a proton in a nucleus is negative in the same way it is negative for an electron trapped in the potential well of a nucleus. A free particle with no kinetic energy has 0 total energy. A bound proton must have energy added to become free.

"I would have added the oxygen binding energy and kinetic energy of the proton together and then subtracted that value from the binding energy of fluorine-18" is exactly right except that the two binding energies are negative.

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  • $\begingroup$ Thanks for the reply, I completely understand it now! $\endgroup$ – Phoooebe Sep 20 '20 at 5:36

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