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9th Class Science Time and Motion Question Bank Motion IIT JEE Objective Problems

  • question_answer
    The initial velocity of a particle\[\overrightarrow{u}=\overrightarrow{4i}+\overrightarrow{3j}\]It is moving with uniform acceleration\[\overrightarrow{a}=0.\overrightarrow{4i}+0.\overrightarrow{3}j\] Its velocity after 10 seconds is

    A)  3 Units                                

    B)  4 units

    C)  5 units                 

    D)  10 units

    Correct Answer: D

    Solution :

    \[\overrightarrow{u}=\overrightarrow{4i}+\overrightarrow{3j}\] \[\overrightarrow{a}=0.\overrightarrow{4i}+0.\overrightarrow{3}j\] velocity after 10 seconds is \[V=\overrightarrow{4i}+\overrightarrow{3j}+(0.\overrightarrow{4i}+0.\overrightarrow{3j})(10)\] \[=\overrightarrow{4i}+\overrightarrow{3j}+\overrightarrow{4i}+\overrightarrow{3j}=\overrightarrow{8i}+\overrightarrow{6j}\] magnitude of \[\vec{v}=\sqrt{64+36}=\sqrt{100}=10\,\,units\]


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