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JEE Main & Advanced JEE Main Paper (Held On 11 April 2014)

  • question_answer
    The initial speed of a bullet fired from a rifle is 630 m/s. The rifle is fired at the centre of a target 700 m away at the same level as the target. How far above the centre of the target ?   [JEE Main Online Paper ( Held On 11 Apirl  2014 )

    A) 1.0m                     

    B) 4.2 m

    C) 6.1 m

    D) 9.8 m

    Correct Answer: C

    Solution :

                                    Let ?t? be the time taken by the bullet to hit the target. \[\therefore \]\[700m=630m{{s}^{-1}}t\]\[\Rightarrow \]\[t=\frac{700m}{630m{{s}^{-1}}}=\frac{10}{9}\sec \] For vertical motion, Here, u = 0 \[\therefore \]\[h=\frac{1}{2}g{{t}^{2}}\]                             \[=\frac{1}{2}\times 10\times {{\left( \frac{10}{9} \right)}^{2}}\] \[=\frac{500}{81}m=6.1m\] Therefore, the rifle must be aimed 6.1 m above the centre of the target to hit the target.                


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