JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Mock Test - Motion in one Dimension

  • question_answer
    Two bikes A and B start from a point. A moves with uniform speed 40 m/s and B starts from rest with uniform acceleration \[2\,m/{{s}^{2}}\]. If B starts at \[t=10\] and A starts from the same point at \[t=10\] s, then the time during the journey in which A was ahead of B is

    A) 20 s                 

    B) 8 s

    C) 10 s                 

    D) A is never ahead of B

    Correct Answer: D

    Solution :

    [d] A will be ahead or B when \[{{x}_{A}}\ge {{x}_{B}}\] \[40(t-10)\ge (0)t+\frac{1}{2}(2){{t}^{2}}\] As A is 10 sec late than B. \[\Rightarrow {{t}^{2}}-40t+400\le 0\] \[\Rightarrow {{(t-20)}^{2}}\le 0\] Which is not possible, so A will never be ahead at B.


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