Question

A black body calorimeter filled with hot water cools from 60°C to 50°C in 4 minutes and 40°C to 30°C in 8 minutes. The approximate temperature of surrounding is (use average method) ​

Answer 1

Assuming the temperature of surrounding be t°C

CASE-1

$\frac{(60−50)}{4min} =k(55−t)(1)$

Again, CASE-2$\frac{(40−30)}{8min} =k(35−t)(2)$

$\frac{(1)}{(2)} = \frac{ \frac{10}{4} }{ \frac{10}{8} } = \frac{(55 - t)}{(35 - t)}$

⇒2(35−t)=55−t

⇒70−2t=55−t

⇒t=15℃