NEET Sample Paper NEET Sample Test Paper-27

  • question_answer
    If R is the radius of the earth and g is the acceleration due to gravity on the earth surface the mean density of earth will be:

    A)  \[\frac{4\pi G}{3g\,R}\]                    

    B)  \[\frac{3\pi G}{4g\,R}\]

    C)  \[\frac{3g}{4\pi RG}\]          

    D)  \[\frac{\pi RG}{2g}\]

    Correct Answer: C

    Solution :

    When the earth in supposed to be a sphere of mean density p, then mass of the earth is will be: \[M=\frac{4}{3}\,\pi {{R}^{3}}\rho \] \[\rho =\frac{3M}{4\pi {{R}^{3}}}\]                      ??(i) Also, from the formula             \[g=\frac{GM}{{{R}^{2}}}\]                     ??(ii) Hence from equations (i) and (ii), we have.             \[\rho =\frac{3g}{4\pi \,GR}\]           


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