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9th Class Science Force and laws of motion Question Bank Force and Laws of Motion

  • question_answer
    A body of mass 300 gm is at rest. What force in Newton will you have to apply to move it through 200 cm in 10 sec.?

    A)  Zero                                     

    B)  12 Newton

    C)  1.2 Newton      

    D)         0.12 Newton  

    Correct Answer: D

    Solution :

     We know, \[s=ut+\frac{1}{2}a{{t}^{2}}\] \[\therefore \]      \[200=0\times 10+\frac{1}{2}a{{(10)}^{2}}\] \[\therefore \]      \[a=40\,\,cm/{{s}^{2}}\] Now,     \[F=m.a\]             \[=300\times 40=12000\,\,dynes\] \[\Rightarrow \]   \[F=\mathbf{0}\cdot \mathbf{12}\,\,\mathbf{Newton}\]


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