Two circular discs A and B with equal radii are blackened. They are heated to same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves?

Question

Two circular discs A and B with equal radii are blackened. They are heated to same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves? (A) A and B have same specific heats (B) Specific heat of A is less (C) Specific heat of B is less (D) Nothing can be said

Tardigrade Admin · Accepted Answer

According to Newton's law of cooling, rate of cooling is given by

(\frac{- d T}{d t}) = \frac{e A σ}{m c} (T^{4} - T_{0}^{4})

where

c

is specific heat of material.
or

(\frac{- d T}{d t}) \propto \frac{1}{c}

ie, rate of cooling varies inversely as specific heat. From the graph, for

A

rate of cooling is larger. Therefore, specific heat of

A

is smaller.

Q. Two circular discs A and B with equal radii are blackened. They are heated to same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves?

A and B have same specific heats

Specific heat of A is less

Specific heat of B is less

Nothing can be said

Q. Two circular discs $A$ and $B$ with equal radii are blackened. They are heated to same temperature and are cooled under identical conditions. What inference do you draw from their cooling curves?