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AFMC AFMC Solved Paper-2006

  • question_answer
    If we throw a body upwards with velocity of 4 m/s, at what height does its kinetic energy reduce to half of the initial value? (Take g= 10 ms-2)                     

    A)  4 m                                       

    B) 2 m

    C) 1 m                                        

    D) 0.4 m

    Correct Answer: D

    Solution :

    Key Idea: At a given height the half of the kinetic energy of the body is equal to its potential energy. Initial kinetic energy of the body                   \[=\frac{1}{2}m{{v}^{2}}\]                  \[=\frac{1}{2}m{{(4)}^{2}}=8m\] Let at height b, the kinetic energy reduces to half, i.e., it becomes 4m. It is also equal to potential energy. Hence,                   \[mgh=4m\] or                  \[h=\frac{4}{g}=\frac{4}{10}=0.4\,m\]


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