SOLUTIONNuclear Physics: Accident in Lab, Wait Time to Enter Room

[petuniac]

QUESTION

in an accident in a lab a radioactive isotope with a half life of 3 days is spilled - as a result the radiation is 8 times the max. permissible amount, how long must workers wait before they can enter the room.

ANSWER

9

COMMENTS

I am not sure where to even start with this one. Please help!

 

[Pengwuino]

Do you know what half life means?

 

[petuniac]

half life is the amount of time it takes for the quantity to reduce to half it's initial value.. in this question it takes 3 days for us to get half of the material

 

[Pengwuino]

So this should be fairly straight forward. If you have 8x the amount and it takes 3 days for half to decay away, how long should it take

 

[petuniac]

huh?

maybe i am missing something here.. but that wouldn't give me 9 as a solution... sorry, I appreciate your help, but am lost on this one... please help

 

[daveb]

If the radiation is 8x the maximum, 3 days later (which is 1 half life) the radiation would be 4x maximum. Can ou go from there?

 

[petuniac]

Thanks. Got it now!