I have this solution that I don't quite understand(adsbygoogle = window.adsbygoogle || []).push({});

d(ro*pi*D^3/6)/d(t)=-kr*Cao*pi*D^2

from here I would have thought to separate the variables and integrate but the solution says

ro/2* d(D)/d(t) = -kr Cao

I guess my question is how are you able to do that? If you take the derivative of D, why is d(D)/d(t) still left behind?

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

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!

# Shrinking core model

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