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JEE Main 2004 (AIEEE) · Work by a Variable Force

Work by a Variable Force question from JEE Main 2004 (AIEEE)

Q23JEE Main 2004 · AIEEEMedium

Work by a Variable Force

A particle moves in a straight line with retardation proportional to its displacement. Its loss of kinetic energy for any displacement xx is proportional to

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Answer: (c)

  1. Retardation a=−kxa = -kx, so vdvdx=−kxv\frac{dv}{dx} = -kx.
  2. Loss of KE =∫0xmkx dx=12mkx2= \int_0^x m k x\,dx = \frac{1}{2}mkx^2
  3. So loss of KE ∝x2\propto x^2; the answer is (c).
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