Question

Consider two hot bodies $B_{1}and{B}_2$ which have temperatures ${100}^{o}Cand{80}^{o}C$ respectively at t=0. The temperature of the surroundings is ${40}^{o}C$. The ratio of the respective rates of cooling $R_{1}and{R}_2$ of these two bodies at t=0 will be

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Initially at t=0
Rate of cooling (R) $\propto$ Fall in temperature of body
$(\theta -{\theta }_0)$
$\Rightarrow \frac{R_1}{R_2}=\frac{{\theta }_1-{\theta }_0}{{\theta }_2-{\theta }_0}=\frac{100-40}{80-40}=\frac{3}{2}$