First slide

Radiation

Question

A body at 50⁰C cools in a surroundings maintained at 30⁰C. The temperature at which the rate of cooling is half that of the begining is

Easy

A

16.3⁰C
B

26.3⁰C
C

40⁰C
D

46.3⁰C

Solution

Rate of colling is given by $\large \frac {-d\theta}{dt}\propto (\theta-\theta_0)$

$\large \left ( \frac {dQ}{dt} \right )_2=\frac 12\left ( \frac {dQ}{dt} \right )_1$
$\large \frac {\left ( \frac {dQ}{dt} \right )_1}{\left ( \frac {dQ}{dt} \right )_2}=\frac {\theta_1-\theta_0}{\theta_2-\theta_0}\Rightarrow \frac {\left ( \frac {dQ}{dt} \right )_1}{\frac 12\left ( \frac {dQ}{dt} \right )_1}=\frac {50-30}{\theta_2-30}$
$\large \theta_2=40^0C$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App