JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2010

  • question_answer
        Two stones are projected with the same velocity but making different angles with the horizontal. Their ranges are equal. If the angle of projection of one is\[\frac{\pi }{3}\]and maximum height is\[{{y}_{1}}\], then the maximum height of other will be

    A)  \[3{{y}_{1}}\]                                   

    B)  \[2{{y}_{1}}\]

    C)  \[\frac{{{y}_{1}}}{2}\]                                   

    D)  \[\frac{{{y}_{1}}}{3}\]

    Correct Answer: D

    Solution :

                     For complementary angles ranges are equal. \[\therefore \]  \[{{\theta }_{1}}=\frac{\pi }{3},\] then      \[{{\theta }_{2}}=\frac{\pi }{2}-\frac{\pi }{3}=\frac{\pi }{6}\] Maximum height for first stone                 \[{{y}_{1}}=\frac{{{u}^{2}}{{\sin }^{2}}{{\theta }_{1}}}{2g}\]                 \[{{y}_{1}}=\frac{{{u}^{2}}{{\sin }^{2}}\frac{\pi }{3}}{2g}\]                 \[=\frac{{{u}^{2}}{{\left( \frac{\sqrt{3}}{2} \right)}^{2}}}{2g}=\frac{3{{u}^{2}}}{8g}\] \[\Rightarrow \]               \[{{u}^{2}}=\frac{8g\,{{y}_{1}}}{3}\] Maximum height for second stone \[{{y}_{2}}=\frac{{{u}^{2}}{{\sin }^{2}}{{\theta }_{2}}}{2g}\] \[=\frac{{{u}^{2}}{{\sin }^{2}}\frac{\pi }{6}}{2g}\] \[=\frac{{{u}^{2}}{{\left( \frac{1}{2} \right)}^{2}}}{2g}=\frac{{{u}^{2}}}{8g}\] \[{{y}_{2}}=\frac{1}{8g}.\frac{8g\,{{y}_{1}}}{3}\]                 \[=\frac{{{y}_{1}}}{3}\]


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