Two particles of mass $m$ each are tied at the ends of a light string of length $2a$ . The whole system is kept on a frictionless horizontal surface with the string held tight so that each mass is at a distance $'a'$ from the centre $P$ (as shown in the figure). Now, the mid-point of the string is pulled vertically upwards with a small but constant force $F$ . As a result, the particles move towards each other on the surface. The magnitude of acceleration, when the separation between them becomes $2x$ , is

818-285

  • A

    $\frac{F}{{2m}}\,\frac{a}{{\sqrt {{a^2} - {x^2}} }}$

  • B

    $\frac{F}{{2m}}\,\frac{x}{{\sqrt {{a^2} - {x^2}} }}$

  • C

    $\frac{F}{{2m}}\,\frac{x}{a}$

  • D

    $\frac{F}{{2m}}\,\frac{{\sqrt {{a^2} - {x^2}} }}{x}$

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