The position vector of a particle changes with time according to the relation $\vec r\left( t \right) = 15{t^2}\hat i + \left( {4 - 20{t^2}} \right)\hat j$. What is the magnitude of the acceleration at $t = 1$ ?

  • [JEE MAIN 2019]
  • A

    $40$

  • B

    $100$

  • C

    $25$

  • D

    $50$

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