One day in the morning, Ramesh filled up 1//3 bucket of hot water from geyser, to take bath, Remaining 2//3 was to be filled by cold water (at room temperature) to bring mixture to a comfortable temperature. Suddenly Ramesh had to attend to something which would take some times, say 5 -10 minutes before he could take bath. Now he had two options : (i) fill the remaining bucket completely by cold water and then attend to the work, (ii) first attend to the work and fill the remaining bucket just before taking bath. Which option do you think would have kept water warmer ? Explain.

Explanation

Option (i) would keep the water warmer than the option (ii) because according to Newton.s law of cooling, the rate of cooling is directly proportional to the temperature difference between the body and its surroundings. In first option by filling the remaining bucket completely by cold water, the temperature difference between hot water and surroundings is less and hence, the rate of cooling will be less.