(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

60Co, half life = 5.2 years, decays by emittion of a beta particle (0.31 MeV) and two gamma particles (1.71MeV and 1.33MeV). what is the minimum initial mass needed of 60Co that will have an activity of at least 10Ci after 30 months?

2. Relevant equations

half life = ln(2)/decasy constant(λ).

Amount of nuclei (N) = rate of decay(R)/decay constant(λ).

N=N(starting) x e^(-λ)(t)

in this equation t is the time between the starting amount and the amount, N, left after the decay.

3. The attempt at a solution

so, i am reasonably competent at the simpler problems involving these formulas, just plug the number in basically. But for this one, i am a little unsure how to include the energy numbers. they dont normally put numbers in if they are not needed.

i can calculate a number which is the amount of nuclei needed to start with, when you have the decay rate they given, and time (i got 1.222x10^20). but this is not the mass.

so im thinking i must have to use the energy in decay with the nuclei number to calculate the mass maybe. or is there a way i can go straight from the number of nuclei to the mass that i am missing? any thoughts would be helpful. thanks

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# Homework Help: Basic nuclear decay

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