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NEET Sample Paper NEET Sample Test Paper-91

  • question_answer
    Consider two hot bodies \[{{B}_{1}}\] and \[{{B}_{2}}\] which have temperatures \[100{}^\circ C\] and \[80{}^\circ C\] respectively at \[t=0\]. The temperature of the surroundings is \[40{}^\circ C\]. 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 \[(\theta -{{\theta }_{0}})\] \[\Rightarrow \]\[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{{{\theta }_{1}}-{{\theta }_{0}}}{{{\theta }_{2}}-{{\theta }_{0}}}=\frac{100-40}{80-40}=\frac{3}{2}\]


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