CET Karnataka Medical CET - Karnataka Medical Solved Paper-2007

  • question_answer
    The acceleration due to gravity becomes \[\left( \frac{g}{2} \right)\] (g = acceleration due to gravity on the surface of the earth) at a height equal to

    A)  4 R

    B)  R

    C)  2 R

    D)  R

    Correct Answer: B

    Solution :

    The acceleration due to gravity\[g=\frac{GM}{{{R}^{2}}}\]At a height h above the earths surface, the acceleration due to gravity is\[g=\frac{GM}{{{(R+h)}^{2}}}\] \[\therefore \] \[\frac{g}{g}={{\left( \frac{R+h}{R} \right)}^{2}}={{\left( 1+\frac{h}{R} \right)}^{2}}\] \[\frac{g}{g}={{\left( 1+\frac{h}{R} \right)}^{-2}}\] \[=\left( 1+\frac{2h}{R} \right)\] but \[g=\frac{g}{2}\] (given) \[\therefore \] \[\frac{g/2}{g}=1-\frac{2h}{R}\] \[\frac{2h}{R}=\frac{1}{2}\] \[h=\frac{R}{4}\]


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