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JEE Main & Advanced Physics Thermometry, Calorimetry & Thermal Expansion Question Bank Self Evaluation Test - Thermal Properties of Matter

  • question_answer
    Consider two hot bodies \[{{\operatorname{B}}_{1}}\] and \[{{B}_{2}}\]which have temperatures \[109{}^\circ C\] and  \[89{}^\circ C\]respectively at t=0. The temperature of the surroundings is\[49{}^\circ C\]. The ratio of the respective rates of cooling \[{{R}_{1}}\] and \[{{R}_{2}}\]of these two bodies at t = 0 will be

    A) \[{{R}_{1}}:{{R}_{2}}=3:2\]    

    B) \[{{R}_{1}}:{{R}_{2}}=5:4\]

    C) \[{{R}_{1}}:{{R}_{2}}=2:3\]    

    D)        \[{{R}_{1}}:{{R}_{2}}=4:5\]

    Correct Answer: A

    Solution :

    [a] Initially at t=0 Rate of cooling (R) \[\propto \] Fall in temperature of body \[\Rightarrow \frac{{{R}_{1}}}{{{R}_{2}}}=\frac{{{\theta }_{1}}-{{\theta }_{0}}}{{{\theta }_{2}}-{{\theta }_{0}}}=\frac{100-40}{80-40}=\frac{3}{2}\]


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