JEE Main & Advanced Physics Two Dimensional Motion JEE PYQ - Two Dimensional Relative Motion

  • question_answer
    A projectile can have the same range R for two angles of projection. If\[{{T}_{1}}\]and\[{{T}_{2}}\]are the times of flights in the two cases, then the product of the two times of flights is directly proportional to     [AIEEE 2004]

    A) \[\frac{1}{{{R}^{2}}}\]

    B) \[\frac{1}{R}\]

    C) R

    D) \[{{R}^{2}}\]

    Correct Answer: C

    Solution :

    [c] We know that range of projectile is same for complementary angles i.e., for\[\theta \]and\[(90{}^\circ -\theta ).\]
    \[\therefore \]      \[{{T}_{1}}=\frac{2u\sin \theta }{g}\]
    \[{{T}_{2}}=\frac{2u\sin ({{90}^{o}}-\theta )}{g}=\frac{2u\cos \theta }{g}\]
    and \[R=\frac{{{u}^{2}}\sin 2\theta }{g}\]
    Therefore, \[{{T}_{1}}{{T}_{2}}=\frac{2u\sin \theta }{g}\times \frac{2u\cos \theta }{g}\]
                            \[=\frac{2{{u}^{2}}(2\sin \theta \cos \theta )}{{{g}^{2}}}\]
                            \[=\frac{2{{u}^{2}}(\sin 2\theta )}{{{g}^{2}}}=\frac{2R}{g}\]
                \[\therefore \]      \[{{T}_{1}}{{T}_{2}}\propto R\]


You need to login to perform this action.
You will be redirected in 3 sec spinner