NEET Sample Paper NEET Sample Test Paper-49

  • question_answer
    A bucket full of hot water cools from \[75{}^\circ C\] to \[70{}^\circ \,C\] in time \[{{T}_{1}}\]), from \[70{}^\circ \,C\] to \[65{}^\circ \,C\] in time \[{{T}_{2}}\] and from \[65{}^\circ C\text{ }to\text{ }60{}^\circ C\] in time T.3, then -

    A) \[{{T}_{1}}={{T}_{2}}={{T}_{3}}~\]           

    B) \[{{T}_{1}}>{{T}_{2}}>{{T}_{3}}\]

    C) \[{{T}_{1}}<{{T}_{2}}<{{T}_{3}}\]              

    D) \[{{T}_{1}}>{{T}_{2}}<{{T}_{3}}\]

    Correct Answer: C

    Solution :

    According to Newton?s law of cooling Rate of cooling \[\propto \] Mean temperature difference \[\Rightarrow \,\,\frac{Fall\,\,in\,\,temperature}{Time}\,\,\propto \,\,\left( \frac{{{\theta }_{1}}+{{\theta }_{2}}}{2}-{{\theta }_{0}} \right)\] \[\because \,\,\,\,{{\left( \frac{{{\theta }_{1}}+{{\theta }_{2}}}{2} \right)}_{1}}\,\,>\,\,{{\left( \frac{{{\theta }_{1}}+{{\theta }_{2}}}{2} \right)}_{2}}\,\,>\,{{\left( \frac{{{\theta }_{1}}+{{\theta }_{2}}}{2} \right)}_{3}}\] \[\Rightarrow \,\,\text{ }{{T}_{1}}<\text{ }{{T}_{2}}<\text{ }{{T}_{3}}\]


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