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JEE Main 2024 (9 Apr, Shift 2) · Rolling Motion

Rolling Motion question from JEE Main 2024 (9 Apr, Shift 2)

Q30JEE Main 2024 · 9 APR · SHIFT 2Medium

Rolling Motion

A circular disc reaches from top to bottom of an inclined plane of length ll. When it slips down the plane, it takes t st\text{ s}. When it rolls down the plane then it takes (α2)1/2t s\left(\frac{\alpha}{2}\right)^{1/2} t\text{ s}, where α\alpha is _________.

Numerical answer type. Work it out, then open the answer.

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Answer: 3

  1. Slipping (no friction): a=gsin⁡θa = g\sin\theta, t=2lgsin⁡θt = \sqrt{\dfrac{2l}{g\sin\theta}}.
  2. Rolling disc: a′=23gsin⁡θa' = \frac{2}{3}g\sin\theta, t′=3lgsin⁡θ=32 tt' = \sqrt{\dfrac{3l}{g\sin\theta}} = \sqrt{\dfrac{3}{2}}\,t.
  3. Comparing with (α2)1/2t\left(\frac{\alpha}{2}\right)^{1/2}t: α=3\alpha = 3.
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