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

  • question_answer
    A boat of mass 3000 kg, initially at rest is pulled by a force of \[\text{1}.\text{8 x 1}{{0}^{\text{4}}}\] Newton through a distance of 3 m. Assuming that the resistance due to water is negligible, velocity of boat is

    A)  6 m/s               

    B)         8 m/s

    C)  9 m/s             

    D)         11 m/s

    Correct Answer: A

    Solution :

     \[a=\frac{F}{m}=\frac{1.8\times {{10}^{4}}}{3000}=6\,\,m/{{s}^{2}}\] We know,\[{{v}^{2}}-{{u}^{2}}=2as\] \[\therefore \]      \[{{v}^{2}}-0=2\times 6\times 3=36\] \[\Rightarrow \]   \[v=6\,\,m/\sec \].


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