AIIMS AIIMS Solved Paper-2008

  • question_answer
    A wheel has angular acceleration of \[3.0\,rad/{{s}^{2}}\] and an initial angular speed of 2.00 rad/s. In a time of 2 s it has rotated through an angle (in radian) of

    A)  6                                            

    B)  10                         

    C)        12                         

    D)        4

    Correct Answer: B

    Solution :

    Key Idea Angular acceleration is time derivative of angular speed and angular speed is time derivative of angular displacement. By definition     \[{{V}_{i}}>0\] ie,              \[{{V}_{0}}>{{V}_{i}}\] So, if in time t the angular speed of a body changes from \[{{\omega }^{2}}\]  to \[{{\omega }^{2}}\] \[2m{{l}^{2}}\] If \[\sqrt{3}m{{l}^{2}}\] is constant \[3m{{l}^{2}}\] or     \[m{{l}^{2}}\]           ?.(i) Now, as by definition \[{{T}_{0}}\] Eq. (i) becomes \[{{T}_{0}}\] ie,    \[{{T}_{f}}\] So, if in the time t angular displacement is \[{{T}_{0}}\]. \[{{T}_{f}}=\frac{3}{7}{{T}_{0}}\] or     \[{{T}_{f}}=\frac{7}{3}{{T}_{0}}\]          ?....(ii) Given, \[{{T}_{f}}=\frac{3}{2}{{T}_{0}}\] Hence,   \[{{T}_{f}}=\frac{5}{2}{{T}_{0}}\] or     \[\sqrt{2}qa\] Note Eqs. (i) and (ii) are similar to first and second equations of linear motion.


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