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NDA 2 2024 GAT, question 124

Topic: Physics

Q124

Given below are the four cases in which certain heat transfer is taking place :

  1. Ice is melting in a glass full of water

  2. Water is boiling in an open container

  3. A metal rod is heated in a furnace

  4. A cup of coffee is allowed to cool on a table

In which of the above cases, the Newton’s Law of Cooling is applicable ?

  1. (a) 1 only
  2. (b) 4 onlyCorrect answer
  3. (c) 1 and 4 only
  4. (d) 1, 2 and 3

Solution.

Answer: (b) 4 only

  1. Cooling coffee under ordinary room conditions is the standard example of Newton's law of cooling: the rate of heat loss is approximately proportional to the temperature difference.
  2. Very high-temperature examples require greater attention to radiation and are less suitable for this simple model.