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A body cools from 60^(@)C,50^(@)C in 10 minutes. If the room temperature is 25^(@)C and assuming Newton's law of cooling to hold good, the temperature of the body at the end of the next 10 minutes will be : |
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Answer» `40^(@)C` `(theta_(1)-theta_(2))/(t)=K[(theta_(1)+theta_(2))/(2)-theta_(0)]` `:.""(60-50)/(10)=K[(60+50)/(2)-25]`. . . (i) In SECOND case, if T be the final temperature after 10 MINUTES. Then `(50-theta)/(10)=K[(50+theta)/(3)-25]` . . . (ii) Dividing (i) by (ii) `(10)/(50-7)=(30)/(theta/2)rArr10theta=60xx50-60T`. `70theta=60xx50` `theta=(60xx50)/(70)=(300)/(7)=42*85^(@)C` Correct CHOICE is (d). |
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