Q 11-10-072JEE MainJEE Main 2023 (6 Apr, Shift 2)Medium
A body cools in $7$ minutes from $60^\circ\text{C}$ to $40^\circ\text{C}$. The temperature of the surrounding is $10^\circ\text{C}$. The temperature of the body after the next $7$ minutes will be
Answer: (D) $28^\circ\text{C}$
$\dfrac{20}{7}=k(50-10)\Rightarrow k=\dfrac{1}{14}$. Next interval: $\dfrac{40-T}{7}=\dfrac1{14}\left(\dfrac{40+T}{2}-10\right)$
$$80-2T=10+\frac T2\ \Rightarrow\ T=28^\circ\text{C}$$
Solution by Sreeraj P, M.Sc Physics