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

Measurements of a certain isotope tell you that the decay rate decreases from 8337 decays/minute to 3174 decays/minute over a period of 5.00 days.

2. Relevant equations

R=Ro.e^-lamda/t

then T1/2 = ln(2)/lamda

3. The attempt at a solution

I converted all the units..

t = 5 days = 432000 seconds

R = 8337 decays/minute = 52.9 decays/s

Ro=3174 decays/minute = 138.95 decays/s

I did:

R=Ro.e^-lamda/t

52.9=138.95 . e^-lamda*432000

lamda = -1.86*10^-6

I am confused.. the lamda should not be a negative number right?

because half-life should be a positive number..

please help me..

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Certain isotope tell you that the decay rate decreases

**Physics Forums | Science Articles, Homework Help, Discussion**