JEE Main & Advanced Physics Work, Energy, Power & Collision / कार्य, ऊर्जा और शक्ति Question Bank Self Evaluation Test - Work, Energy and Power

  • question_answer
    An iron ball of mass m, suspended by a light inextensible string of length from a fixed point, 0, is shifted by an angle \[{{\theta }_{0}}\] as shown so as to strike the vertical wall perpendicularly. The ' maximum angle made by the string with vertical after the first collision, if e is the coefficient of restitution, is

    A) \[{{\sin }^{-1}}\left\{ 1-{{e}^{2}}\left( 1-\cos {{\theta }_{0}} \right) \right\}\]

    B) \[{{\cos }^{-1}}\left\{ 1-{{e}^{2}}\left( 1-\cos {{\theta }_{0}} \right) \right\}\]

    C) \[{{\tan }^{-1}}\left\{ 1-{{e}^{2}}\left( 1-\cos {{\theta }_{0}} \right) \right\}\]

    D) Zero

    Correct Answer: B

    Solution :

    [b] Speed just before collision \[=\sqrt{2g\ell (1-\cos {{\theta }_{0}})}\] Speed just after collision \[=e\sqrt{2g\ell (1-\cos {{\theta }_{0}})}\] \[\frac{1}{2}m{{e}^{2}}[2g\ell (1-\cos {{\theta }_{0}})]=mg\ell (1-\cos \theta )\]From conservation of energy, \[\therefore \theta ={{\cos }^{-1}}\left\{ 1-{{e}^{2}}(1-\cos {{\theta }_{0}}) \right\}\]


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