Question

A body cools down from 70°c to 60°c in 5 minutes. It will cool down from 65°c to 60°c in

Answer 1

Explanation:

$\huge\bf{\mid{\overline{\underline{ANSWER:-}}\mid}}$

$\huge\bold{Formula:-} \\ \\ \frac{intial \: temp - final \: temp}{time} = k (average \: of \: temp - surrounding temp) \\ \\ \frac{70 - 60}{5} = k ( 65 - 25) ......[assuming \: that \: surrounding \: temp \: is \: 298 K] \\ \\ 2 = k (40) \\ \\ k = \frac{1}{20} = 0.05 \\ \\ Now, \: for \: 65 \to 60 \implies \\ \\ \frac{65-60}{x} = 0.05 \times ( 62.5 - 25) \\ \\ \frac{5}{x} = 0.05 \times 37.5 \\ \\ x = \frac{5 \times 20}{37.5} \\ \\ \huge\boxed{x = 2.66 \: mins}$