Manipal Engineering Manipal Engineering Solved Paper-2014

  • question_answer
    A wheel is rotating with an angular speed of 20 rad/s. It is stopped to rest by applying a constant torque in 4s. If the moment of inertia of the wheel about its axis is 0.20 kg/m2, then the work done by the torque in two seconds will be

    A) 10 J                                        

    B) 20 J

    C) 30 J                                        

    D) 40 J

    Correct Answer: C

    Solution :

    \[\frac{{{m}_{2}}g}{(4{{m}_{1}}+{{m}_{2}})}\] So angular   retardation \[\frac{2{{m}_{2}}g}{(4{{m}_{1}}+{{m}_{2}})}\] Now,    angular    speed    after    2s \[\frac{2{{m}_{1}}g}{({{m}_{1}}+4{{m}_{2}})}\] Work done by torque in 2 s = loss in kinetic energy \[\frac{2{{m}_{1}}g}{({{m}_{1}}+{{m}_{2}})}\] \[F(x)=-kx+a{{x}^{3}}\] \[x\ge 0,\]


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