NEET Physics Question - Thermal Physics

A beaker full of hot water is kept in a room. If it cools from $80^\circ\text{C}$ to $75^\circ\text{C}$ in $t_1$ minutes, from $75^\circ\text{C}$ to $70^\circ\text{C}$ in $t_2$ minutes and from $70^\circ\text{C}$ to $65^\circ\text{C}$ in $t_3$ minutes, then: (1995)

$t_1 < t_2 < t_3$

$t_1 > t_2 > t_3$

$t_1 = t_2 = t_3$

$t_1 < t_2 = t_3$

Solution:

According to Newton's law of cooling, the rate of cooling is directly proportional to the temperature difference between the body and surroundings. As the water cools, the temperature difference decreases, slowing the rate of cooling. Thus, successive intervals take more time, giving $t_1 < t_2 < t_3$.

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