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

  • question_answer
    When a body is projected vertically up from the ground with certain velocity, its potential energy and kinetic energy at a point A are in the ratio 2 : 3. If the same body is projected with double the previous velocity, then at the same point A the ratio of its potential energy to kinetic energy is

    A) 9 : 1

    B) 2 : 9

    C) 1 : 9

    D) 9 : 2

    Correct Answer: C

    Solution :

    [c] Let E be the total energy then \[\frac{P.E}{K.E}=\frac{mgh}{E-mgh}=\frac{2}{3}\Rightarrow E=\frac{5}{2}mgh\] When velocity is double then inital energy becomes 4E. So,       \[\frac{mgh}{4E-mgh}=NL=\frac{mgh}{10mgh-mgh}\] On solving we get\[\frac{P.E}{K.E}=\frac{1}{9}\].


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