A block moving horizontally on a smooth surface with a speed of $40\, {m} / {s}$ splits into two parts with masses in the ratio of $1: 2$. If the smaller part moves at $60\, {m} / {s}$ in the same direction, then the fractional change in kinetic energy is :-

  • [JEE MAIN 2021]
  • A

    $\frac{1}{3}$

  • B

    $\frac{2}{3}$

  • C

    $\frac{1}{8}$

  • D

    $\frac{1}{4}$

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