Question

HELP !!!!! How much of a radioactive kind of uranium will be left after 120 seconds if the half-life is 30 seconds and you start with 560 grams ?

Answer 1

half life means that every 30 seconds, the mass of the uranium will be decreased in half

so after 30 seconds, if the original mass is 560 grams, then the mass of uranium will be 280 g

after another 30 seconds, the mass of uranium will be halved again,
so it goes from 280 -> 140

and etc and etc

Answer 2

I had 140 before and it was wrongggg

Answer 3

???

Answer 4

140 is the mass after 60 seconds

Answer 5

at 90 seconds, which is an extra 30 seconds from 60 seconds

half of 140 is ?

Answer 6

70

Answer 7

yeah thats wrong too .

Answer 8

read your question again...

Answer 9

its asking for the mass at 120 seconds

not 60 seconds and not 90 seconds

Answer 10

if at 0 seconds the mass is 560
at 30 seconds the mass is 280
at 60 seconds the mass is 140
at 90 seconds the mass is 70
then at 120 seconds...

Answer 11

There's a half-life formula that I believe was taught in Algebra 2 that really helps with this:\[A=a(\frac{ 1 }{ 2 })^{t/h}\]
Where,
A = final amount/mass, typically in grams or kilograms
a = the initial amount/mass, typically in grams or kilograms
t = The amount of time
h = the half-life

Remember to stay consistent. If you are given kilograms, make sure all mass units are in kg as well. Hope this helps.

Answer 12

yayy i got it its 35 lol

Answer 13

and it did help

Answer 14

thanks :)

Answer 15

@xoxox123 You're welcome :)