Manipal Medical Manipal Medical Solved Paper-2013

  • question_answer
    When temperature of an ideal gas is increased from\[27{}^\circ C\]to\[277{}^\circ C,\]its rms speed is changed  rom 400 m/s to\[{{\upsilon }_{s}}\].The Vg is

    A)  516m/s

    B)  450 m/s

    C)  310 m/s

    D)  746 m/s

    Correct Answer: A

    Solution :

     The root mean square velocity of the gas is given by \[{{v}_{rms}}=\sqrt{\frac{3RT}{M}}\] where, R is gas constant, T is absolute temperature and m is the molecular weight of the gas. \[{{T}_{1}}=27{}^\circ C=273+27=300K\] \[{{T}_{2}}=227{}^\circ C=273+227=500K\] \[\frac{{{v}_{1}}}{{{v}_{2}}}=\sqrt{\frac{300}{500}}=\sqrt{\frac{3}{5}}\] Given       \[{{v}_{1}}=400\,m/s,{{v}_{2}}={{v}_{s}}\] \[{{v}_{s}}=\sqrt{\frac{5}{3}}\times 400\] \[=129\times 400\] \[=516.39\text{ }m/s=516\text{ }m/s\] Note If the absolute temperature of the gas become zero then the motion of molecules will cease.


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