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DUMET Medical DUMET Medical Solved Paper-2005

  • question_answer
    A flat mirror revolves at a constant angular velocity making 2rev/s. With what velocity will a light spot move along a spherical screen with a radius of 10 m, if the mirror is at a centre of curvature of the screen?

    A)  251.2 m/s    

    B)  261.2m/s

    C)  .271.2m/s    

    D)  241.2m/s

    Correct Answer: A

    Solution :

     Key Idea: One revolution covers 2 n radians. The relation between angular velocity (co) and linear velocity (v) is \[v=r\,\omega \] where r is radius of path. Angular velocity of mirror \[=4\pi \] rad/s. Angular velocity of reflected ray \[=2\times 4\,\pi =8\,\pi \] rad/s \[\therefore \] \[v=10\times 8\,\pi =80\times 3.14=251.2\,m/s\].


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