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

  • question_answer
    Two particles are projected simultaneously from the level ground as shown in figure. They may collide after a time:

    A) \[\frac{x\sin {{\theta }_{2}}_{\,}}{{{u}_{1}}}\]

    B)        \[\frac{x\text{ cos}{{\theta }_{2}}_{\,}}{{{u}_{2}}}\]

    C) \[\frac{x\sin {{\theta }_{2}}_{\,}}{{{u}_{1}}\sin \left( {{\theta }_{2}}-{{\theta }_{1}} \right)}\]

    D)        \[\frac{x\sin {{\theta }_{1}}_{\,}}{{{u}_{2}}\sin \left( {{\theta }_{2}}-{{\theta }_{1}} \right)}\]

    Correct Answer: C

    Solution :

    [c] \[x+{{u}_{2}}\cos {{\theta }_{2}}t={{u}_{1}}\cos {{\theta }_{1}}t\]
    \[\therefore \,\,\,\,\,\,\,\,t=\frac{x}{{{u}_{1}}\cos {{\theta }_{1}}-{{u}_{2}}\cos {{\theta }_{2}}}\]            ?(i)
    Also  \[{{u}_{1}}\sin {{\theta }_{1}}={{u}_{2}}\sin {{\theta }_{2}}\]                ?(ii)
    After solving above equations, we get
    \[t=\frac{x\,\sin {{\theta }_{2}}}{u{{ & }_{1}}\sin \left( {{\theta }_{2}}-{{\theta }_{1}} \right)}\]


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