CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2008

  • question_answer
    Two particles A and B are projected with same speed so that the ratio of their maximum heights reached is 3:1. If the speed of A is doubled without altering other parameters, the ratio of the horizontal ranges attained by A and B is

    A)  \[1:1\]                 

    B)         \[2:1\]                 

    C)  \[4:1\]                 

    D)         \[3:2\]

    E)  \[4:3\]

    Correct Answer: C

    Solution :

    \[H=\frac{{{u}^{2}}{{\sin }^{2}}\theta }{2g}\]or\[\frac{{{H}_{1}}}{{{H}_{2}}}=\frac{{{u}^{2}}{{\sin }^{2}}{{\theta }_{1}}}{{{u}^{2}}{{\sin }^{2}}{{\theta }_{2}}}\] Or \[\frac{3}{1}=\frac{{{\sin }^{2}}{{\theta }_{1}}}{{{\sin }^{2}}{{\theta }_{2}}}\]or\[\frac{\sin {{\theta }_{1}}}{\sin {{\theta }_{2}}}=\frac{\sqrt{3}}{1}\] Logically, we can conclude that                 \[{{\theta }_{1}}={{60}^{o}},{{\theta }_{2}}={{30}^{o}}\] Again     \[R=\frac{{{u}^{2}}\sin 2\theta }{g}\] Or           \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{4{{u}^{2}}\sin 2{{\theta }_{1}}}{{{u}^{2}}\sin 2{{\theta }_{2}}}\] Or           \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{4\sin 2({{60}^{o}})}{\sin 2(30{}^\circ )}=\frac{4\sin 120{}^\circ }{\sin 60{}^\circ }\] Or           \[\frac{{{R}_{1}}}{{{R}_{2}}}=\frac{4\times \frac{\sqrt{3}}{2}}{\frac{\sqrt{3}}{2}}=4\]


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