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

  • question_answer
    A body of mass 2 kg is acted upon by two forces each of magnitude 1 Newton, making an angle of \[60{}^\circ \] with each other. The net acceleration of the body (in\[\text{m}/{{\text{s}}^{\text{2}}}\]) is

    A)  \[\frac{\sqrt{2}}{3}\]                                    

    B)  \[\frac{\sqrt{3}}{2}\]  

    C)  0.5                  

    D)         1.0

    Correct Answer: B

    Solution :

     By the law of parallelogram of forces             \[F={{(1)}^{2}}+{{(1)}^{2}}+2\times 1\times 1\times \cos {{60}^{o}}\]                   \[=1+1+2\times \frac{1}{2}=3\] \[\Rightarrow \]   \[\sqrt{F}=\sqrt{3}Newton\] Now      \[F=ma\] \[\Rightarrow \]   \[a=\frac{F}{m}=\frac{\sqrt{\mathbf{3}}}{\mathbf{2}}\mathbf{m/}{{\mathbf{s}}^{\mathbf{2}}}\]


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