A block of metal is heated to a temperature much higher than the room temperature and allowed to cool in a room free from air currents. Which of the following curves correctly represents the rate of cooling ?

Concept Videos :-

#52-Newton's Law of Cooling
#54-Solved-Examples-25
#56-Solved-Examples-26

Concept Questions :-

Newton's law of cooling

(b) According to Newton's law of cooling

Rate of cooling ∝ Temperature difference
-dtθ-θ0-dt=αθ-θ0  (α= constant)
θ1θdθθ-θ0=-α0tdtθ=θ0+θi-θ0e-αt
This relation tells us that, temperature of the body varies exponentially with time from θi to θ0
Hence graph (b) is correct.

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