Uttarakhand PMT Uttarakhand PMT Solved Paper-2006

  • question_answer
    A body of specific heat\[0.2\text{ }kcal/kg{}^\circ C\]is heated through 1000C. The percentage increase in its mass is :

    A)  9%             

    B)  \[9.3\times {{11}^{-11}}%\]

    C)  10%            

    D)  none of these

    Correct Answer: B

    Solution :

     Heat taken by the given body \[=mc\Delta \theta \] {specific heat of body\[=0.2\text{ }kcal/kg{}^\circ C,\]final temperature of the body\[=100{}^\circ C\]} \[\Delta E=m\times 0.2\times 100\] \[=20\text{ }m\text{ }kcal\] \[=20m\times 4.2\times {{10}^{3}}J\] Now, gain in mass is given by \[\Delta m=\frac{\Delta E}{{{c}^{2}}}\] \[(\because E=m{{c}^{2}})\] \[=\frac{20m\times 4.2\times {{10}^{3}}}{{{(3\times {{10}^{8}})}^{2}}}\] Therefore, percentage increase in mass is given by \[=\frac{\Delta m}{m}\times 100\] \[=\frac{20m\times 4.2\times {{10}^{3}}}{{{(3\times {{10}^{8}})}^{2}}\times m}\times 100\] \[=9.3\times {{10}^{-11}}%\]


You need to login to perform this action.
You will be redirected in 3 sec spinner