Q. Liquid is filled in a vessel which is kept in a room with temperature $20℃$. When the temperature of the liquid is $80℃$, then it loses heat at the rate of $60\ cal/s$. What will be the rate of loss of heat when the temperature of the liquid is $40℃$
A) $180\ cal/s$
B) $40\ cal/s$
C) $30\ cal/s$
D) $20\ cal/s$
Explanation
(d) Rate of loss of heat $\left( \frac{\mathrm{\Delta}Q}{t} \right) \propto$ temperature difference $\mathrm{\Delta}\theta$
$\frac{\left( \frac{\mathrm{\Delta}Q}{t} \right)_{1}}{\left( \frac{\mathrm{\Delta}Q}{t} \right)_{2}} = \frac{\mathrm{\Delta}\theta_{2}}{\mathrm{\Delta}\theta_{1}} \Rightarrow \frac{60}{\left( \frac{\mathrm{\Delta}Q}{t} \right)_{2}} = \frac{80 - 20}{40 - 20} \Rightarrow \left( \frac{\mathrm{\Delta}Q}{t} \right)_{2} = \frac{20cal}{s}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.