I'm a web developer and I have to change an online course. The course teaches Advanced Nuclear Theory. In the 'Mass Defect and Binding Energy' chapter, it has this formula:
$$\Delta M = Z(m_p) + N(m_n) - \frac{A}{Z}(M).$$
In the formula above, the letter 'p' and 'n' are written in subscript, and for the 'AZM' part, the letter A (written in superscript) is above the letter Z (which is in subscript). Above this equation, this is written
1/1(p) + 1/0(n) -> 2/1(D)
mass of proton = 1.007272 u
mass of neutron = 1.008665 u
mass of deuterium nuclear = 2.013553 u
. Below the equation which I wrote above (delta M = Z(mp) + N(mn) - A/Z(M)), the worker / user is asked to fill in the blank:
∆M = __ x __ + __ x __ - __
B.E. of nucleaus = 931.5 x __ MeV
When the neutron and proton combine, the nuclear force pulling them together does __ MeV of work.
Now, can anyone tell me what the correct answers are to the blanks? I'm just a web developer and I have to write a program which checks that the user filled in the correct answers, but I do not know the correct answers. I have some knowledge of physics and I'm guessing mp = mass of proton, mn = mass of neutron and then M = mass of deuterium nucleus, but what about the other blanks?
Answer
On the Wikipedia page for the semi-empirical mass formula (based on the Gamow liquid drop model of nuclei) it basically says that the mass defect $\Delta M$ is given by the difference in the masses of the unbound protons and neutrons $Zm_p+Nm_n$ minus the actual mass of the nucleus, $^A_ZM$ (the rest of the semi-empirical formula is not needed here).
The only other bit of trivia you need to know is that 1 amu of mass is the equivalent of 931.5 MeV energy.
So in order, the blanks should be typeset as $Z,m_p,N,m_n,^A_ZM,\Delta M,$ and 2.22 MeV.
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