AMU Medical AMU Solved Paper-1997

  • question_answer
    Consider two unequal masses\[{{m}_{2}}>{{m}_{1}}\]connected by a string which passes over a frictionless and massless pulley. The tension T in the string is

    A)  \[T=2\frac{m_{1}^{2}+m_{2}^{2}}{{{m}_{1}}+{{m}_{2}}}g\]

    B)  \[T=\frac{2{{m}_{1}}{{m}_{2}}}{{{m}_{1}}+{{m}_{2}}}g\]

    C)  \[T=\frac{2m_{2}^{2}+m_{1}^{2}}{{{m}_{1}}+{{m}_{2}}}g\]

    D)  \[T=2({{m}_{1}}+{{m}_{2}})g\]

    Correct Answer: B

    Solution :

    : Let tension in string = T acceleration\[=a\] \[\therefore \] For greater mass, \[{{m}_{2}}g-T={{m}_{2}}a\] For smaller mass, \[T-{{m}_{1}}g={{m}_{1}}a\] Divide them to eleminate a \[\therefore \]\[\frac{{{m}_{2}}g-T}{T-{{m}_{1}}g}=\frac{{{m}_{2}}a}{{{m}_{1}}a}\] Or \[{{m}_{1}}{{m}_{2}}g-{{m}_{1}}T={{m}_{2}}T-{{m}_{1}}{{m}_{2}}g\] Or \[2{{m}_{1}}{{m}_{2}}g={{m}_{1}}T+{{m}_{2}}T=T({{m}_{1}}+{{m}_{2}})g\] Or \[T=\frac{2{{m}_{1}}{{m}_{2}}}{({{m}_{1}}+{{m}_{2}})}g\]


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