RAJASTHAN ­ PET Rajasthan PET Solved Paper-2008

  • question_answer
    The particle of mass 50 kg is at rest. The work done to accelerates it by 20 in/s in 10 s is

    A)  \[{{10}^{3}}J\]            

    B)  \[{{10}^{4}}J\]

    C)  \[2\times {{10}^{3}}J\]         

    D)  \[4\times {{10}^{4}}J\]

    Correct Answer: B

    Solution :

     \[v=u+at\] \[20=0+a\times 10\] \[20=a\times 10\] \[a=2m/{{s}^{2}}\] then         \[s=ut+\frac{1}{2}a{{t}^{2}}\] \[s=0+\frac{1}{2}\times 2\times 10\times 10\] \[s=100m\] Work done    \[W=F\times s\] or          \[W=ma\times s\] \[\therefore \] \[W=50\times 2\times 100\] \[W=10000={{10}^{4}}J\]


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