Chhattisgarh PMT Chhattisgarh PMT Solved Paper-2011

  • question_answer
    The velocity at the maximum height of a projectile is half its initial velocity of projection \[u\] Its range on the horizontal plane is

    A) \[\frac{\sqrt{3}{{u}^{2}}}{2g}\]                                 

    B) \[\frac{{{u}^{2}}}{3g}\]

    C) \[\frac{3{{u}^{2}}}{2g}\]                                               

    D) \[\frac{3{{u}^{2}}}{g}\]

    Correct Answer: A

    Solution :

    There is only horizontal component of velocity at the highest point because at highest point vertical component of velocity is zero, body begins to come downwards from the highest point. \[\therefore \]  \[u\,\cos \,\theta =\frac{u}{2}\]                 \[\,\cos \,\theta =\frac{1}{2}=\cos \,\,{{60}^{o}}\] \[\Rightarrow \]               \[\theta ={{60}^{o}}\] Range   \[R=\frac{2{{u}^{2}}\,\sin \theta \,cos\theta }{g}\]                 \[R=\frac{2{{u}^{2}}\,\times \,\sin \,{{60}^{o}}\,\cos {{60}^{o}}}{g}\]                 \[R=\frac{\sqrt{3}{{u}^{2}}}{2g}\]      


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