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JEE Main 2023 (6 Apr, Shift 1) · Centripetal Acceleration & Force

Centripetal Acceleration & Force question from JEE Main 2023 (6 Apr, Shift 1)

Q23JEE Main 2023 · 6 APR · SHIFT 1Medium

Centripetal Acceleration & Force

A small block of mass 100 g100\text{ g} is tied to a spring of spring constant 7.5 N/m7.5\text{ N/m} and length 20 cm20\text{ cm}. The other end of spring is fixed at a particular point A. If the block moves in a circular path on a smooth horizontal surface with constant angular velocity 5 rad/s5\text{ rad/s} about point AA, then tension in the spring is -

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Answer: (c)

  1. Spring force gives the centripetal force: kx=mω2(l+x)kx = m\omega^2(l + x).
  2. mω2=0.1×25=2.5m\omega^2 = 0.1 \times 25 = 2.5, so 7.5x=2.5(0.2+x)7.5x = 2.5(0.2 + x).
  3. 5x=0.5⇒x=0.1 m5x = 0.5 \Rightarrow x = 0.1\text{ m}
  4. Tension =kx=7.5×0.1=0.75 N= kx = 7.5 \times 0.1 = 0.75\text{ N}. So the answer is (c) 0.75 N.
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