Questions
A body in a room cools from to in 5 minutes. The time taken to cool from to is
detailed solution
Correct option is C
θ1=85∘c θ2=80∘cθ2=80∘c θ3=75∘ct1=5 minutest2=?θ0=constant=temperature of surrounding from newton law of cooling dθdt1=-kθ1+θ22-θ0---(1) substitute given values in above equationθ1-θ25=-k85+802-θ085-805=-k82.52-θ055=-k41.25-24---(2)∵Room temperature is 24°C second part of question, given values substitute in eqn(1)80-75t2=-k80+752-θ05t2=-k38.75-24---(3) eqn(2) ÷eqn(3) t2= 5.47mint2is more than 5 minutesSimilar Questions
A body cools down from 60°C to 55°C in 30 s. Using Newton’s law of cooling, calculate the approximate time taken by same body to cool down from 5 5°C
to 50°C. Assume that the temperature of surroundings is 45°C.
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