Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

Q#1 Initially there are 6*10upper 9 radioactive ofelement w (decay constant 0.17

ID: 1681103 • Letter: Q

Question

Q#1 Initially there are 6*10upper 9 radioactive ofelement   w (decay constant 0.173/day) in a sample. As anucleus of w decays, it converts 2.67*10 upper -28 kg of itsmass to energy and release the energy. How much time (in days) isrequired for the sample to release a total of 7.2*10 uper -4j? (a) 0 (b) 0.000290 (c)0.00571 (d)0.00943 (e)0.0137 (a,b)0.0290 (a,c)0.0571 (a,d)0.290 (a,e)0.571 (b,c)3.29 Q#1 Initially there are 6*10upper 9 radioactive ofelement   w (decay constant 0.173/day) in a sample. As anucleus of w decays, it converts 2.67*10 upper -28 kg of itsmass to energy and release the energy. How much time (in days) isrequired for the sample to release a total of 7.2*10 uper -4j? (a) 0 (b) 0.000290 (c)0.00571 (d)0.00943 (e)0.0137 (a,b)0.0290 (a,c)0.0571 (a,d)0.290 (a,e)0.571 (b,c)3.29

Explanation / Answer

N = 6*109, = 0.173/day, m = 2.67*10-28kg, E = 7.2*10-4 J, find t initial number of nucleus = N after t, number = Ne-t number reduced = N(1 - e-t) for each nucleus, energy created = mc2 after t, energy generated = mc2N(1 -e-t) = E t = (-1/)ln[1 - E/(mc2N)] = 0.029 days answer: (a,b)