Advertisements
Advertisements
Question
An ordinary electric fan does not cool the air, still it gives comfort in summer. Explain
Solution
An ordinary electric fan does not cool the air, still it gives comfort in summer because it circulates the air present in the room. Due to this, evaporation takes place and we feel cooler.
APPEARS IN
RELATED QUESTIONS
A body cools from 80 °C to 50 °C in 5 minutes. Calculate the time it takes to cool from 60 °C to 30 °C. The temperature of the surroundings is 20 °C.
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?
A body cools down from 65°C to 60°C in minutes. It will cool down from 60°C to 55°C in
Answer the following question.
State Newton’s law of cooling and explain how it can be experimentally verified.
Solve the following problem.
A metal sphere cools at the rate of 0.05 ºC/s when its temperature is 70 ºC and at the rate of 0.025 ºC/s when its temperature is 50 ºC. Determine the temperature of the surroundings and find the rate of cooling when the temperature of the metal sphere is 40 ºC.
A metal sphere cools from 80 °C to 60 °C in 6 min. How much time with it take to cool from 60 °C to 40 °C if the room temperature is 30 °C?
A bucket full of hot water cools from 85 °C to 80 °C in time T1, from 80 °C to 75 °C in time T2 and from 75 °C to 70 °C in time T3, then ______.
Rate of cooling of a body is 0.4 °C/min when excess temperature is 20 °C. The proportionality constant is ______.
Newton's law of cooling leads to the expression:
Two circular discs A and B with equal radii are blackened. They are heated to the same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves?
A cup of coffee cools from 90°C to 80°C in t minutes, when the room temperature is 20°C. The time taken for a similar cup of coffee to cool from 80°C to 60°C at a room temperature same at 20°C is ______
A cup of coffee cools from 90°C to 80°C in t minutes, when the room temperature is 20°C. The time taken by a similar cup of coffee to cool from 80°C to 60°C at a room temperature same at 20°C is ______.
Is the bulb of a thermometer made of diathermic or adiabatic wall?
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.
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 ______.
In 5 minutes, a body cools from 75°C to 65°C at a room temperature of 25°C. The temperature of the body at the end of the next 5 minutes is ______°C.
