9th Class Science Gravitation and Floatation Question Bank Gravitation Summative Objective Problems

  • question_answer
    If the distance between two particles is increased by 2%, then the force of attraction between them will be:

    A)  Decreases by 6%   

    B)  Decreases by 4%

    C)  Increases by 4%              

    D)  Increases by 6%

    Correct Answer: B

    Solution :

      If the distance between particles is increased by 2%, \[F\propto \frac{1}{{{r}^{2}}}\Rightarrow \frac{dF}{dr}=\frac{d}{dr}({{r}^{-2}})=\frac{-2}{r}\therefore dF=\frac{-2}{r}dr\] \[or\,\,\frac{dF}{F}\times 100=\frac{-2}{r}\frac{dr}{F}=-2r\,\,dr\times 100\] Given, \[\frac{dr}{r}\times 100=2%\] \[\therefore \,\,dF%=%\]decrease.


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