A glass full of hot milk is poured

Question:

A glass full of hot milk is poured on the table. It begins to cool gradually. Which of the following is correct?

(a) the rate of cooling is constant till milk attains the temperature of the surrounding

(b) the temperature of milk falls off exponentially with time

(c) while cooling, there is a flow of heat from milk to the surrounding as well as from surrounding to the milk but the net flow of heat is from milk to the surrounding and that is why it cools

(d) all three phenomena, conduction, convection, and radiation are responsible for the loss of heat from milk to the surroundings

Solution:

The correct answers are

(b) the temperature of milk falls off exponentially with time

(c) while cooling, there is a flow of heat from milk to the surrounding as well as from surrounding to the milk but the net flow of heat is from milk to the surrounding and that is why it cools

(d) all three phenomena, conduction, convection, and radiation are responsible for the loss of heat from milk to the surroundings

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