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WB JEE Medical WB JEE Medical Solved Paper-2015

  • question_answer
    Three bodies of the same material and having masses \[m,m\]and 3m are at temperatures \[40{{\,}^{o}}C,\,\,50{{\,}^{o}}C\]and \[60{{\,}^{o}}C,\] respectively. If the bodies are brought in thermal contact, the final temperature will be

    A) \[45{{\,}^{o}}C\]   

    B) \[54{{\,}^{o}}C\]  

    C) \[52{{\,}^{o}}C\]  

    D) \[48{{\,}^{o}}C\]

    Correct Answer: B

    Solution :

     Let the final temperature after the masses in thermal contact is \[\theta ,\] then from the principle  of calorimetry. Heat lost = Heat gained                    \[\Rightarrow \]\[3\,ms(60-\theta )=ms(\theta -50)+ms\,(\theta -40)\] \[\Rightarrow \]\[3(60-\theta )=\theta -50+\theta -40\] \[\Rightarrow \]\[180-3\theta =2\theta -90\] \[\theta =\frac{270}{5}=54{{\,}^{o}}C\]


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