Uttarakhand PMT Uttarakhand PMT Solved Paper-2008

  • question_answer
    How much work must be done by a force on 50 kg body in order to accelerate it from rest to 20 m/s in 10 s?

    A)  \[{{10}^{3}}J\]         

    B)  \[{{10}^{4}}J\]

    C)  \[2\times {{10}^{3}}J\]      

    D)  \[4\times {{10}^{4}}J\]

    Correct Answer: B

    Solution :

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


You need to login to perform this action.
You will be redirected in 3 sec spinner