J & K CET Engineering J and K - CET Engineering Solved Paper-2003

  • question_answer
    A particle moves along the x-axis from \[x={{x}_{1}}\] to \[x={{x}_{2}}\] under the action of a force given by\[F=2\text{ }x\]. Then the work done in the process is

    A)  zero         

    B)  \[{{x}_{2}}^{2}-{{x}_{1}}^{2}\]

    C)  \[2{{x}_{2}}({{x}_{2}}-{{x}_{1}})\]

    D)  \[2{{x}_{1}}({{x}_{1}}-{{x}_{2}})\]

    Correct Answer: B

    Solution :

    Mechanical work (W) is the force applied through a distance, defined mathematically as the line integral of a scalar product of force (F) and displacement (dx) vectors. \[W=\int{Fdx}\] Given, \[F=2x,\] Using   \[\int{{{x}^{n}}dx}=\frac{{{x}^{n+1}}}{n+1}\] \[\therefore \] \[W=\int_{{{x}_{1}}}^{{{x}_{2}}}{2x\,\,dx=2\left[ \frac{{{x}^{2}}}{2} \right]_{{{x}_{1}}}^{{{x}_{2}}}}\] \[=({{x}_{2}}^{2}-{{x}_{1}}^{2})\]


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