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JEE Main 2022 (30 Jul, Shift 2) · Centripetal Acceleration & Force

Centripetal Acceleration & Force question from JEE Main 2022 (30 Jul, Shift 2)

Q29JEE Main 2022 · 30 JUL · SHIFT 2Medium

Centripetal Acceleration & Force

A mass of 0.5 kg0.5\text{ kg} is attached to one end of a massless spring whose natural length is 1 m1\text{ m} and spring constant is 800 N/m800\text{ N/m} The other end of the spring is fixed while the mass moves in a circular path in a horizontal plane with an angular speed of 20 rad/s20\text{ rad/s}. The extension in the length of the spring will be:

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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=0.5×400=200m\omega^2 = 0.5 \times 400 = 200, so 800x=200(1+x)800x = 200(1 + x).
  3. 600x=200⇒x=13 m600x = 200 \Rightarrow x = \frac{1}{3}\text{ m}
  4. So the answer is (c) 13 m\frac{1}{3}\text{ m}.
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