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MGIMS WARDHA MGIMS WARDHA Solved Paper-2006

  • question_answer
    A flat mirror revolves at a constant angular velocity making 2 revolutions/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) 261/2 m/s

    C) 271.2 m/s                           

    D) 241/2 m/s

    Correct Answer: A

    Solution :

    Angular velocity of the mirror \[=2rev/s\] \[=2\times 2\pi \text{ }rad/s\] Angular velocity of the reflected ray \[=2\times 4\pi \] \[=8\pi \text{ }rad/s\] Velocity of light spot over the screen                 \[v=r\omega \]                 \[=10\times 8\pi \]                 \[=80\pi \] \[=251.2\text{ }m/s\]


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