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Phy 242
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 **
Test 4 Question
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Part of the solution for Practice Problem Set 7 Number 20:
mass defect = 2 ( 5 - .0032 ) amu - [ ( 9 - .00309 ) amu - ( 1 + .00867 ) amu ] = .00856 amu = 13.69 * 10^-30 kg
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I am confused by how to calculate the mass defect. When I try calculating this I'm not getting the same '.00856 amu' that you are getting. I don't understand what I am doing wrong. What's going on with the plus and minus signs within the parenthesis? I'm using the order of operations and adding and subtracting where I should, but I'm still not getting the right answer. I have to take my test tomorrow (Thursday August 1st). So if I come across this question I will do my best to walk you through the steps but I'm getting stuck at this calculation of the mass defect.
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I don't have the information of the given problem but I believe you have two of the first particle yielding the second and third particles, so that the calculation should read
2 ( 5 - .0032 ) amu - [ ( 9 - .00309 ) amu + ( 1 + .00867 ) amu ] =
( 10 - .0064 - 9 + .00309 - 1 - .00867) amu =
(-.0064 + .00309 - .00837) amu
This comes out to about -.012 amu, indicating that this much mass is lost in the process.
Obviously there are errors in that solution.
You expect the final mass to be less than the initial mass, so to get the mass defect you subtract the final from the initial.
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