Advertisements
Advertisements
प्रश्न
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.
Advertisements
उत्तर
Using the concept of Newton’s law of cooling, we can say that rate of cooling is directly proportional to the difference in the temperature of the body and surroundings.
According to the first option, the water should be warmer, as the difference between the temperature of the surroundings and the water is small, therefore, less heat is lost.
According to the second option, the heat lost is more, as the difference between the surroundings and water is large.
APPEARS IN
संबंधित प्रश्न
On a hot summer day we want to cool our room by opening the refrigerator door and closing all the windows and doors. Will the process work?
On a cold winter night you are asked to sit on a chair. Would you like to choose a metal chair or a wooden chair? Both are kept in the same lawn and are at the same temperature.
An ordinary electric fan does not cool the air, still it gives comfort in summer. Explain
A body cools down from 65°C to 60°C in minutes. It will cool down from 60°C to 55°C in
Rate of cooling of a body is 0.4 °C/min when excess temperature is 20 °C. The proportionality constant is ______.
A liquid with a certain surface area takes 10 minutes to cool from 80° C to 70° C. The time taken by it to cool from 80° C to 60° C is [The surrounding temperature being 40° C] ____________.
According to Newton's law of cooling, the rate of cooling of the body is proportional to (Δθ), where Δθ is the difference between the temperature of the body and the surroundings, and n is equal to ______.
According to Newton's law of cooling, how does the rate of cooling depend on temperature?
In \[\frac{dT}{dt}\] = C(T−T₀), what does the constant C represent?
What is the shape of the cooling curve T vs t?
If we plot \[\frac{dT}{dt}\] vs (T−T₀), what graph do we get?
A body cools from 60°C to 40°C in 6 minutes. After next 6 minutes its temperature will be (Temperature of the surroundings is 10°C) ______.
A body cools from temperature \[(3\theta)^{\circ}C\] to \[(2\theta)^{\circ}C\] in 10 minute. Then it cools from \[(2\theta)^{\circ}C\] to \[(\theta_1)^{\circ}C\] in next 10 minutes. The room temperature is \[(\theta)^{\circ}C.\] Assuming that the newton's law of cooling is applicable the value of \[(\theta_1)^{\circ}C\] is ______.
Why is the calorimeter kept in open air or a constant-temperature enclosure during Newton’s law of cooling experiment?
A body is cooling from 80°C to 60°C in a room at 30°C. Compared to the time taken to cool from 60°C to 40°C, the time taken to cool from 80°C to 60°C will be ______.
The cooling curve of a hot body is a graph of temperature T versus time t. What is the correct description of this curve?
A metal ball cools at 2.0°C/min when its temperature is 60°C and the surrounding temperature is 20°C. What will be its rate of cooling when its temperature drops to 30°C?
