Question

a cup of coffee cools from 90 degree Celsius to 80degree Celsius in t minutes, when the room temperature is 20 degree Celsius . The time taken by a similar cup of coffee to cool from 80 degree celsius to 60 degree Celsius at a room temperature same at 20 degree Celsius is​

Answer 1

Answer:

i don't no, sorry. pls solve it by yourself, try nd try till u succeed

Answer 2

Given:

$\text { According to Newton's law of coollng, }$

$\frac{T_{1}-T_{2}}{t}=\mathrm{K}\left[\frac{T_{1}+T_{2}}{2}-T_{0}\right]$

$\text { For } 1^{\text {st }} \text { cup of coffee, }$

$\Rightarrow \frac{90-80}{t}=\mathrm{K}\left[\frac{90+80}{2}-20\right] . .(1)$

$\text { For } 2^{\text {nd }} \text { cup of coffee, }$

$\Rightarrow \frac{80-60}{t}=\mathrm{K}\left[\frac{80+60}{2}-20\right] . .(2)$

$\text { Dlvide (1) by (2), }$

$\begin{array}{l}\frac{t^{\prime}}{2 t}=\frac{65}{60} \\\Rightarrow t^{\prime}=\frac{13}{5} t\end{array}$

the answer is13/5t