JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Critical Thinking Questions

  • question_answer
    A ball is projected upwards from a height \[h\] above the surface of the earth with velocity \[v\]. The time at which the ball strikes the ground is 

    A)             \[\frac{v}{g}+\frac{2hg}{\sqrt{2}}\]

    B)               \[\frac{v}{g}\left[ 1-\sqrt{1+\frac{2h}{g}} \right]\]

    C)             \[\frac{v}{g}\left[ 1+\sqrt{1+\frac{2gh}{{{v}^{2}}}} \right]\]     

    D)             \[\frac{v}{g}\left[ 1+\sqrt{{{v}^{2}}+\frac{2g}{h}} \right]\]

    Correct Answer: C

    Solution :

                    Since direction of v is opposite to the direction of g and h so from equation of motion              \[h=-vt+\frac{1}{2}g{{t}^{2}}\]             \[\Rightarrow g{{t}^{2}}-2vt-2h=0\]             \[\Rightarrow t=\frac{2v\pm \sqrt{4{{v}^{2}}+8gh}}{2g}\]             \[\Rightarrow t=\frac{v}{g}\left[ 1+\sqrt{1+\frac{2gh}{{{v}^{2}}}} \right]\]


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