NEET Sample Paper NEET Sample Test Paper-74

  • question_answer
    The distance between the sun and the earth is R. The angular momentum of earth around the sun is proportional to

    A)  \[{{R}^{2/3}}\]                      

    B)  R                  

    C)  \[{{R}^{1/2}}\]                                  

    D)  \[{{R}^{3/2}}\]

    Correct Answer: C

    Solution :

    Angular momentum of earth around the sun \[\operatorname{L} = l\omega  = m{{R}^{2}}\omega \] \[\operatorname{L} \propto  m{{R}^{2}}\omega \]                               ... (i) As,         \[{{T}^{2}}\,\,\propto \,\,{{R}^{3}}\]                         (Kepler?s law) \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,T\,\,\propto \,\,{{R}^{3/2}}\] Now,     \[\omega =\frac{2\pi }{T}\propto {{R}^{-3/2}}\]                    ... (ii) Now, putting the value of \[\omega \] from Eq. (ii),to (i) \[\therefore \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,L\propto {{R}^{2}}\,{{R}^{-3/2}}\] \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,L\propto \sqrt{R}\]


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