#$&*
Phy 122
Your 'question form' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
** Question Form_labelMessages **
Negative Mass Defect
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I took another practice test and came across this problem
Two identical hypothetical nuclei, each with mass ( 3 - .0041) amu, fuse to form a nucleus with mass ( 5 - .00399) amu and a neutron, whose mass is about 1.000867 amu. How much energy would be given off if .58 kg of these nuclei fused?
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When I set up the arithmetic for the mass defect I get
mass defect = 2(3-.0041)amu - (5-.00399)amu - 1.000867 amu
mass defect = 5.9918 amu -4.99601 amu - 1.000867 amu
mass defect = -.005077 amu
I did not think it was possible to have a negative mass defect, but I'm not 100% confident of that. I may be calculating something wrong here.
If I am correct and this was just an tic in the random number generator - what could I do if I saw this on a real test?
???Could I acknowledge that it shouldn't be negative, but then go on to solve showing what the energy would be if I just used the absolute value of the amu???
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That would be fine, and it would get you full credit.
Another appropriate answer would simply be that the nuclei wouldn't fuse.
However I don't intentionally throw 'curve balls' on this test, so if you didn't do OK on the problem I would assume it's because of the error and wouldn't count it.
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