i am trying to solve this [t is time and T is temperature] to find the time t,

6450*Pi*(0.00185^2)*(0.0625)*836

dt = --------------------------------------------- dT

(1.2^2)*7.5 - 108*Pi*0.00185*0.25*T

between the limits 0 and 180degC

i have tried & got this answer, t = 3.6236 ln (10.8 - 0.156923*T)

and when solving between the limits, I am getting error because of ln (10.8-0.156923(180)) which is negative.

can someone help me:(