Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2011

  • question_answer
    A ship of mass \[3\times {{10}^{7}}kg\] initially at rest is pulled by a force of \[5\times {{10}^{4}}N\] through a distance of 3 m. Assuming that the resistance due to water is negligible. The speed of the ship will be

    A)  0.1 m/s                               

    B)  1.5 m/s

    C)  5 m/s                                   

    D)  60 m/s

    Correct Answer: A

    Solution :

    From Newton's 2nd law \[F=ma\]                ...(i) From equation of motion substituting                 \[{{v}^{2}}={{u}^{2}}+2as\]                 \[{{v}^{2}}=0+2as\]                 \[a=\frac{{{v}^{2}}}{2s}\]                              ?.(ii) From Eqs. (i) and (ii)                 \[F=\frac{m{{v}^{2}}}{2s}\]          ?..(iii) Given,                   \[F=5\times {{10}^{4}}N\]                                 \[m=3\times {{10}^{7}}kg\]                                 \[s=3m\] \[\therefore \]  \[5\times {{10}^{4}}=3\times {{10}^{7}}\times \frac{{{v}^{2}}}{2\times 3}\]                 \[{{v}^{2}}=\frac{5\times {{10}^{4}}\times 2}{{{10}^{7}}}\] or            \[{{v}^{2}}={{10}^{-2}}m/s\] So,          \[v={{10}^{-1}}m/s=0.1m/s\]


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