JEE Main & Advanced Physics Two Dimensional Motion Question Bank Self Evaluation Test - Motion in a Plane

  • question_answer
    The angle which the velocity vector of a projectile thrown with a velocity v at an angle \[\theta \] to the horizontal will make with the horizontal after time t of its being thrown up is:

    A) \[\theta \]                                  

    B) \[{{\tan }^{-1}}\left( \theta /\text{t} \right)\]

    C) \[{{\tan }^{-1}}\left( \frac{\text{v cos}\theta }{\text{v sin}\theta -\text{gt}} \right)\]          

    D) \[{{\tan }^{-1}}\left( \frac{\text{v sin}\theta -\text{gt}}{\text{v cos}\theta } \right)\]

    Correct Answer: D

    Solution :

    [d] Horizontally after time
    \[v\,\,\cos \theta =v\,\,\cos \beta \]                        ?(i)
    [\[\beta \]= angle with horizontal after time t]
    Vertically, \[v\,\,\sin \theta -gt=v\,\,\sin \,\beta \]     ?(ii)
    Dividing on (ii)/ (i) we get \[\tan \beta =\frac{v\sin \theta -\text{gt}}{v\cos \theta }\]\[\tan \beta =\frac{v\sin \theta -\text{gt}}{v\cos \theta }\Rightarrow \beta ={{\tan }^{-1}}\left( \frac{v\sin \theta -gt}{v\cos \theta } \right)\]


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