BHU PMT BHU PMT Solved Paper-2004

  • question_answer
    A body, thrown upwards with some velocity reaches the maximum height of 50 m. Another body with double the mass thrown up with double the initial velocity will reach a maximum height of:                                              [BHU PMT-2004]

    A)  100 m                                  

    B)  200 m

    C)  300 m                                  

    D)  400 m

    Correct Answer: B

    Solution :

                     Key Idea:  At maximum height, final velocity is zero. From equation of motion, we have                                                 \[{{v}^{2}}={{u}^{2}}-2gh\] Where \[v\] is final velocity, \[u\] is initial velocity, \[h\] is height and \[g\] is acceleration due to gravity. Since body reaches maximum height in both cases, hence final velocity is zero. \[\therefore \]                  \[v=0\] \[\Rightarrow \]                               \[\frac{{{h}_{1}}}{{{h}_{2}}}=\frac{u_{1}^{2}}{u_{2}^{2}}\] Given, \[{{u}_{2}}=2{{u}_{1}},{{v}_{1}}=u\] \[\therefore \]  \[\frac{{{h}_{1}}}{{{h}_{2}}}=\frac{{{u}^{2}}}{{{\left( 2u \right)}^{2}}}=\frac{1}{4}\] \[\Rightarrow \]               \[{{h}_{2}}=4{{h}_{1}}=4\times 50=200\,m.\] Note: Maximum height attained does not depend upon the mass of the body.


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