A boy’s catapult is made of rubber cord which is $42\, cm$ long, with $6\, mm$ diameter of cross -section and of negligible mass. The boy keeps a stone weighing $0.02\, kg$ on it and stretches the cord by $20\, cm$ by applying a constant force. When released, the stone flies off with a velocity of $20\, ms^{-1}$. Neglect the change in the area of cross section of the cord while stretched. The Young’s modulus of rubber is closest to

  • [JEE MAIN 2019]
  • A

    $10^3\, Nm^{-2}$

  • B

    $10^6\, Nm^{-2}$

  • C

    $10^8\, Nm^{-2}$

  • D

    $10^4\, Nm^{-2}$

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