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JEE Main 2026 (6 Apr, Shift 2) · Rolling Motion

Rolling Motion question from JEE Main 2026 (6 Apr, Shift 2)

Q8JEE Main 2026 · 6 APR · SHIFT 2Medium

Rolling Motion

A solid sphere (A)(A) of mass 5m5m and a spherical shell (B)(B) of mass mm, both having same radius, are placed on a rough surface. When a force of same magnitude is applied tangentially at the highest points of AA and BB, they start rolling without slipping with an acceleration of aAa_A and aBa_B, respectively. The ratio of aAa_A and aBa_B is ______.

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Answer: (a)

  1. Force FF at top, friction ff forward at bottom, I=kMR2I = kMR^2: F+f=MaF + f = Ma and (F−f)R=kMR2aR(F - f)R = kMR^2\dfrac{a}{R}.
  2. Adding: 2F=(1+k)Ma⇒a=2F(1+k)M2F = (1+k)Ma \Rightarrow a = \dfrac{2F}{(1+k)M}.
  3. Sphere A (k=25k = \frac{2}{5}, mass 5m5m): aA=2F7ma_A = \dfrac{2F}{7m}. Shell B (k=23k = \frac{2}{3}, mass mm): aB=6F5ma_B = \dfrac{6F}{5m}.
  4. aAaB=27×56=521\dfrac{a_A}{a_B} = \dfrac{2}{7}\times\dfrac{5}{6} = \dfrac{5}{21}.
  5. So the answer is (a) 5:215 : 21.
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